NEUROSCIENCE

Neural correlates of consciousness (general)

02.00-- Abstract No:1323

How to take consciousness seriously in cognitive neuroscience

A.Revonsuo (Center for Cognitive Neuroscience, Department of Philosophy , University of Turku, FIN-20014 Turku, Finland <antti.revonsuo@utu.fi>)

The starting point for the cognitive neuroscience of consciousness is the view that consciousness is in the brain. If this assumption is taken seriously, where does it lead us, theoretically and empirically? Biological systems consist of different levels of organization, and biological theories of corresponding levels of description and explanation. Thus, cognitive neuroscience should reconceptualize consciousness as the phenomenal level of organization in the brain. The phenomenal level should first be systematically described on its own terms, for the underlying neural mechanisms cannot be discovered until there is a clear conception what the mechanisms are supposed to be mechanisms of. In order to describe the phenomenal level, we should define a useful metaphor and a model system to depict this level of organization. I propose that the dreaming brain is a good model system for consciousness: it isolates consciousness from input and output. It also leads to the Virtual Reality Metaphor: Consciousness is the brain’s natural Virtual Reality or Telepresence system: we feel directly present in the world, although all of it is going on somewhere inside the brain (Revonsuo 1995). The phenomenal level is, essentially, the brain’s current on-line, real-time model of the world. What does the existence of such a phenomenal level of organization in the brain mean for empirical cognitive neuroscience? We should naturally try to discover the levels of organization in the brain at which the phenomenal level is realized and figure out whether our current methods of functional brain imaging are appropriate for revealing such a level.

The neural correlates of consciousness reflect events in the brain closely related to events at the phenomenal level. A major feature of the phenomenal level is that it is a visuo-spatial world of perceived objects. Therefore, a good starting point for the cognitive neuroscience of consciousness is to try to reveal the neural correlates of the visual awareness of objects. Since we only have access to human phenomenology, it is reasonable to use human observers in the experiments. The phenomenal level is probably closely related to electrophysiological events in the brain, but e.g. PET and fMRI directly reflect haemodynamics, not electrophysiological activity. If we want to observe, with high temporal resolution, the electrophysiological changes taking place in the brain at the very moment a perceptual object emergers into visual awareness in a human subject, we need to use EEG or MEG.

 We have in this spirit tested two hypotheses, originally presented by Crick and Koch (1990, 1995), regarding the neural correlates of visual awareness. First, in which visual cortical areas are the neural correlates of visual awareness located? Crick & Koch argue that primates are not directly aware of neural activation in V1, but that they may be aware of activity in other visual cortical areas. We measured cortical magnetic responses (122-channel MEG) to visual awareness of objects in an object detection task (Vanni, Revonsuo, Saarinen & Hari, 1996; Vanni, Revonsuo & Hari, 1997). Second, we tested the hypothesis that high-frequency neural oscillations around 40-Hz are associated with the binding of visual percepts into coherent wholes. We recorded EEG (20 electrodes) in a binocular fusion task in which the subjects perceived the same stimulus (a random dot stereogram) first as an incoherent collection of random dots from which suddenly emerged a coherent three-dimensional Gestalt (Revonsuo, Wilenius-Emet, Kuusela & Lehto, 1997). Both of the Crick & Koch hypotheses were supported by our results.

References

Crick F & Koch C.(1990) Towards a neurobiological theory of consciousness. Seminars in the Neurosciences 2, 263-275.

Crick F & Koch C (1995) Are we aware of neural activity in primary visual cortex? Nature 375: 121-123.

Revonsuo A. (1995) Consciousness, dreams, and virtual realities. Philosophical Psychology 8: 35-58.

Revonsuo A, Wilenius-Emet M, Kuusela J & Lehto M (1997) The neural generation of a unified illusion in human vision. NeuroReport 8 (18): 3867-3870.

Vanni S, Revonsuo A, Saarinen J & Hari R. (1996) Visual awareness of objects correlates with activity of right occipital cortex. NeuroReport 8 (1): 183-186.

Vanni S, Revonsuo A & Hari R (1997) Modulation of parieto-occipital alpha rhythym during object detection. The Journal of Neuroscience 17, 7141-7147.


02.01-- Abstract No:778

Higher consciousness - the domains of the human psyche

P.J.Snow (Cerebral & Sensory Functions Unit, Department of Anatomical Sciences, University of Queensland, St. Lucia, Qld 4072, Australia<P.Snow@mailbox.uq.oz.au>) , D.C.Trussell

Whatever consciousness itself is, it does seem apparent that it is a phenomenon elaborated by activity patterns within the cerebral cortex. Phylogenetic studies of the mammalian brain have shown that an increasing proportion of the cerebral cortex lies within that enigmatic realm we call the prefrontal lobes. The development of the prefrontal lobes is accompanied by an increasing complexity in social behaviour, that is especially clear from the anthropological reconstructions of the level of behavioural copmplexity of our hominid ancestors. Like the rest of the cortex, the prefrontal lobes may be subdivided into a number of cytoarchitectonic areas only some of which are found in lower mammals. On the basis of what is known about post-prefrontal cortex it would seem reasonable to assume that each of the cytoarchitectonic areas of the prefrontal lobes has a unique functional significance. Ascribing function to individual prefrontal areas, is, however, not a simple task as the prefrontal lobes are far removed from the tangible sensory-motor functions that are elaborated by post-prefrontal regions. In relation to this it is fascinating to find that within the prefrontal lobes of the most behaviourally advanced, non-human primates are to be found all the cytoarchitectonic areas present in the prefrontal lobes of modern man. Yet if we look back in evolution through the non-primate mammals we can discern a complete absence of those prefrontal areas, that during human ontogeny, are the last cortical regions to fully develop. In this paper we will present work correlating the behavioural strategies of representative primate, and non-primate mammals, at various representative levels of phylogenenetic development, with the component areas of their prefrontal lobes and the connections of these prefrontal areas to other brain regions. We will develop the thesis that from these studies it is possible to discern that part of cortical tissue, that is responsible for those domains of conscious experience that we broadly call the psyche. Furthermore that it is possible to subdivide the area responsible for conceptual thought and/or ideation and representational memory (ie mind) from those areas responsible for our consciousness of those entities (eg. moods, emotions, suffeing, pleasure etc) that we broadly refer to as limbic or paralimbic in origin. We submit that understanding these correlations between function, structure, ontogeny and phylogeny is not only of philosophical, religious and scientific interest but that it has great potential for our appreciation of the biological origin of psychiatric disease and the role of early environment to the normal/correct development of the human psyche.


02.01-- Abstract No:886

Cortical architectonics and qualia: the problem of the undifferentiated substratum

C.U.M.Smith (Department of Vision Sciences, Aston University, Birmingham, B47ET, UK<c.u.m.smith@aston.ac.uk>)

How is it that phenomenological consciousness is so various yet its anatomical substratum so uniform? The paper begins by briefly reviewing the historical bias towards mental 'atomism' from the phrenology of Gall and Spurzheim through the localisation of the Brodmanns to present day neuroimaging (1) . This 'atomistic', 'locationalist', bias has clear relationships with a dominant associationist psychology. The paper then goes on to review modern understanding of the structure and interconnexity of the neocortex with particular reference to the sensory areas and shows that at all levels from molecule, through fibril to cell to minicolumn, the histology is unchanged from one area to the other. It is also noted that not only structure but also activity - biophysics and cell physiology - are identical from one area to the next. Assuming a dual-aspect psychoneural identity theory the question becomes insistent: how can such an undifferentiated physical matrix correlate with so various a sensory subjectivity? The historical bias towards mental 'atomism' or 'units of feeling', seems to be just that - a prejudice. Attention is then directed to experiments which emphasise the lability and holism of the cortex: the embryological 'rewiring' experiments of Métin, O'Leary, Sur and others and the numerous experiments which show the adaptive response of the cortex to peripheral wounds and other insult. It is proposed that the subjectivity of the early cortex is much less differentiated than in the adult. The phenomenon of synaesthesia is discussed as supporting this conjecture. I argue, in conclusion, that sensory subjectivity 'crystallises' from an initial 'blooming, buzzing' subjectivity in response to the biological need to differentiate between greatly different types of environmental happenings impingeing on the sensory endings. It is a 'global' phenomenon so that each quale is the subjective aspect of a state of the entire cortex, rather as a Chladni figure is the outcome of a complex vibration in the underlying plate. The conjecture implies that although a given sensory quale and the brain state with which it is correlated remains invariant over time in an individual, it is likely to differ from one individual to the next; the conjecture would also go far towards anwering the so-called 'binding problem'.

1. See C.U.M.Smith, 1992, 'A century of cortical architectonics, J.Hist.Neurosci., 1, 201-218


02.01-- Abstract No:964

The 'cognitive iceberg' model of awareness and qualia

E.Ransford (DRET/DCE 16 bis, ave Prieur de la Côte d'Or, 94114 Arcueil Cedex, France<ransford @ etca.fr>)

To be sure, this gives an invaluable insight into the inner workings of our awareness-begetting brains. However, this descriptive account falls woefully short, explanation-wise, of providing any telling clue. This being so, can we go further in our knowledge and understanding of the neural correlates of consciousness, and get an inkling as to what physical processes yield some awareness -- and above all, why they do so? This raises the hard problem of consciousness (Chalmers, 1995) .

In a bid to tackle it, I put forward a tentative approach which goes all the way down to the microphysical level; whilst being geared to address the acknowledged nonlocal 'distributedness' of consciousness. This approach bears a definite resemblance to the orch OR thesis of Hameroff and Penrose (1996) . It leads to the cognitive iceberg model of perceptual awareness.

Unsurprisingly enough, this iceberg is made on the one hand of an "underwater part" -- where incoming sensory stimuli are encoded in the shape of what I call the suprels. (For instance, visual suprels are typically churned out in the relevant visual cortical areas -- like V4 for the 'color' sub-modality.) Here they remain unconscious. [This former stage is that of the preconscious brain processing. The "underwater" part could be better termed the underaware part...] Thereafter, on the other hand, they are sent straight into the "tip" of the cognitive iceberg -- where specific micro-structures (which I christen the paralgens) readily turn them into qualia. [This latter stage is that of the conscious brain processing. One might expect it to be carried out, at least partially, in the higher associative areas of the cortical prefrontal lobe.]

The nature (and location) of the suprels and paralgens will be discussed in some detail, in line with current data and proposals; such as that of Crick and Koch (1996) , Hameroff and Penrose (1996) , and Newman (1997) . (We shall see that some of these paralgens -- if they exist at all -- are likely to be tucked inside the postsynaptic NMDA receptors found on the dendritic synapses of large glutamatergic pyramidal cells in the fifth layer of the neocortex . . . ) .

Furthermore, it will be argued that the above model may shed new, if provisional, light on such conundrums as: the binding problem; the nature of declarative memory; the 'upshot problem', whereby "what we are conscious of is the result [or upshot] of computations rather than the [neural] computations themselves" (Johnson-Laird, 1993) ; and the 'causal paradox' surrounding the "interactions between consciousness and brain" (Velmans, 1997) . (This 'paradox' arises when considering the first-person versus the third-person accounts; it will be discussed in view of Velmans' perspectival switching proposal.)

Lastly, I shall touch upon the possibility of exo-biological awareness. This will lead me to sketch out, in keeping with the foregoing, a broad-brush -- and admittedly highly speculative -- 5-step program aimed at spelling out how to achieve it eventually.


02.01-- Abstract No:993

Newly elucidated circuitry subserving the selective gating of fronto-hippocampal systems contributing to the stream of consciousness: A model for the modulation of attention by affective states and episodic representations

J.Newman (Colorado Neurological Institute<Newmanjb@aol.com>) , A.Grace

As noted in a recent review by Hameroff, "a prevalent and seemingly reasonable model of the neural correlate' of consciousness involves thalamo-cortical feedback loops with hippocampal connections". These T-C loops pass through the reticular thalamic nucleus (RTN) , which is known to modulate a broad spectrum of EEG oscillatory activities. Moreover, RTN is widely thought to subserve essential "gating" functions allowing the cortex to selectively control/fliter the flow of perceptual information through the central nevous system. Newman has postulated that RTN serves as a "nexus" for attentional systems in posterior and prefrontal cortex (PfC) essential to the generation of the stream of consciousness. Grace et al. have proposed that nucleus accumbens (NAc) serves related functions in gating PfC and limbic inputs to this RTN-thalamocortical system.

The present paper offers an integrated model for the selective activation of specific thalamo-cortical circuits via PfC and hippocampal projections upon NAc. This parallel-distribtued circuitry (including topographic projections between PfC, cingulate cortex, medial-dorsal nucleus (MD) , and RTN) is proposed to allow outputs from prefrontal and hippocampal systems to focus attention towards a paticular stimulus or cognitive state, based upon affective associations and episodic representations contributing to the stream of consciousness. NAc-mediated activity may ultimately adjust the level of rhythmicity within an RTN-MD system by acting on RTN neuron dendrites, which have been proposed to "tune" its response. This RTN-wide tuning of its dendro-dentritic network may globally control the flow of sensory inputs to the cortex. It is hypothesized that this complex circuitry could provide the basis by which a single, coherent flow of information emerges our of the diverse activties of the CNS.

Detailed anatomical and physiological evidence elucidating this global attentional circuitry will be presented. This evidence will then be interpreted within the context of Newman's general theory of the Extended Reticular-Thalamic Activating System (ERTAS) , and Grace's model of gating of prefrontal throughput in the nucleus accumbens by limbic system afferents. In particular, Grace has proposed that there are two sets of afferent inputs to the accumbens that contribute to gating of prefrontal-accumbens-thalamocortical system activation: a context-related system driven by input from the hippocampal subiculum; and an affectively driven event-related system mediated by inputs from the amygdala.


02.01-- Abstract No:1014

Spectral EEG coherence in visual hallucinations: Possible "binding" of visual information

H.D.Abraham (Alcohol and Drug Treatment Service, Butler Hospital, 345 Blackstone Blvd., Providence, RI 02906, USA<abraham@butler.org>) , F.H.Duffy

Broad distribution of elements of visual perception has prompted the thesis that such elements are bound together to form a conscious image. We hypothesized that binding of visual information at the level of the cerebral cortex in humans occurs by increases in spectral synchrony of electrical potentials measured by quantitative electroencephalography (qEEG) . To test this hypothesis we compared 38 patients with chronic, continuous visual hallucinations following LSD to 76 non-hallucinating controls. All hallucinators fulfilled diagnostic criteria for hallucinogen persisting perception disorder (HPPD) , and had used LSD a mean of 8.6 years earlier. Common hallucinations included geometric shapes, flashes of light, myriad dots, and afterimages. The commonest precipitant was entering into a darkened room. Previously we showed these subjects exhibit disinhibition of visual processing psychophysically and electrophysiologically. To test the hypothesis that an alteration in spectral synchrony was associated with visual hallucinations, we compared the synchrony of electrical potentials of hallucinators and controls by measuring qEEG coherence between adjacent and distant electrode pairs across the cerebrum. Coherence was measured by measuring the potentials of qEEG data sampled and sorted in 16 2 Hz spectral bins across 32 Hz. All patients were drug free for at least ten days, verified by serial urine screens. Data were obtained from 20 scalp electrodes and four other bipolar electrodes strategically placed to monitor artifact, stored on analog tape, converted into digital signals, and analyzed to compare the EEG spectra, and visual and auditory evoked potentials between hallucinators with controls. A minimum of one minute of artifact free EEG was used to form the final mean spectrum for each subject.

We found that active hallucinators exhibited increased coherence in adjacent electrodes with eyes closed, when hallucinations were increased, and showed decreased coherence in adjacent electrodes with eyes open. The topographic distribution of increased cortical coherence involved the occipital and the nondominant temporoparietal regions. The decrease in coherence in the eyes open state was found in a generalized pattern across the cortex. We also found that cerebral coherence in hallucinators correlates with shortened latency in visually evoked potentials and an increased alpha frequency over the occiput, two measures of cortical disinhibition. Finally, a strong canonical correlation between occipital coherence and measures of cortical disinhibition was also noted. It is suggested that in humans the conscious perception of post-LSD visual hallucinations is associated with an increase in synchrony of cortical tissue in the occipital and nondominant temporoparietal regions, and that localized cortical synchrony may depend on disinhibition of that region.


02.01-- Abstract No:1033

Experimental predictions based on the statistical and temporal aspects of a hypothetical neural mechanism for subjectivity

S.A.Helekar (Stuttering Center Speech Motor Control Laboratory, Department of Neurology and Division of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, U.S.A.<shelekar@bcm.tmc.edu>) , J-BLe Pichon

Neurophysiological and psychophysical studies on conscious perception have led several investigators to propose that temporal representation and processing of information may play a pivotal role in the neural mechanisms that give rise to consciousness. In an effort to unify and extend some of these proposals, we have recently proposed a hypothesis for the neural basis of subjectivity. This hypothesis comprises the following three features. 1) Elementary subjective experiences may be encoded by a small basic set of temporal patterns of neuronal activity using a non-arbitrary correlation or coding scheme. 2) The intensity of these experiences may be proportional to the number of successive repetitions of their coding patterns. 3) Temporally extended combinations of subsets of elementary patterns may give rise to complex experiences.

We are currently attempting to formalize this hypothesis using statistical concepts derived from Queuing Theory. If one assumes that spontaneous occurrences of temporal patterns of activity, generated by independently active groups of neurons, follow a Poisson distribution, then order-independent sequences of a fixed number of specific patterns occurring within a certain interval of time would follow a gamma distribution. According to our hypothesis, the latter sequences could be defined as the neuronal correlates of complex subjective experiences. Therefore, an important new prediction of the above hypothesis is that the frequency distribution of intervals between spontaneous occurrences of subjective experiences would approximate a gamma distribution. This would also be true of situations wherein an ambiguous constant stimulus elicits multiple equiprobable percepts. In these cases, the intervals between perceptual transitions would follow a gamma distribution. The latter prediction is supported by experiments involving multistable percepts such as the Necker cube illusion, the face-vase illusion and binocular rivalry situations.

Four important predictions stemming from the temporal features of the hypothesis are as follows. i) The mechanism underlying the occurrence of subjective experiences is dependent on a temporally extended process whose duration is prolonged by increasing the intensity or complexity of the experiences. ii) It is primarily sequential in nature, in that complex subjective experiences are generated by sequentially concatenated sets of experience-coding temporal activity patterns. iii) It involves an iterative process consisting of multiple successive repetitions of a given experience-coding pattern. iv) The coding pattern sequence underlying a quasi-instantaneous complex experience is time-insensitive, in the sense that the temporal order of individual patterns within this sequence is of no consequence to the nature and content of the subjective experience. Each of the above predictions is supported by psychophysical evidence obtained from the phenomena of forward and backward masking, temporal integration, perceptual fusion, pre-perceptual images and attention-based motion illusions.

By combining the methodologies of visual masking experiments with those involved in measurements of reaction times and perceptual thresholds, we have designed experiments to perform quantitative tests of the above predictions. We propose to test all predictions resulting from temporal and statistical aspects of the hypothesis under a single uniform set of conditions. We will present and discuss all of the findings resulting from these experiments and their interpretation.


02.01-- Abstract No:1270

Mirror neurons: from grasping to language

V.Gallese (Istituto di Fisiologia Umana. University of Parma, Parma, Italy<fisioum@symbolic.pr.it>)

Brain's function can be accounted for only by considering the dynamic interplay between the biological agent, who possesses the brain, and the external world. This theoretical premise has two correlated implications: first, if we want to clarify the way in which our brain "recreates" the reality we are living in, it is hardly possible to conceive perception as totally independent from action. Second, we must study the brain trying as much as possible to bring the "world" into the laboratory, by using a "naturalistic" approach. This approach, when applied to neurophysiology, consists in choosing the most appropriate way of testing neurons activity, by figuring out what would be the stimuli or the behavioral situation that more closely approximate what the animal we are recording from would experience in its natural environment.

By using a naturalistic approach, area F5 of the ventral premotor cortex of the macaque monkey was investigated with the single neuron recording tecnique.

A newly discovered class of F5 grasping neurons, Mirror neurons, will be described. These visuomotor neurons respond both when a particular action is performed by the recorded monkey AND when the same action performed by another individual is observed. All mirror neurons discharge during specific goal-related motor acts. Grasping, manipulating and placing objects are by far the most effective actions triggering their motor response. The most effective visual stimuli triggering mirror neurons visual responses are actions in which the experimenter, or a second monkey, interacts with objects with their hand or with their mouth. In almost all mirror neurons a clear correlation between the most effective observed action and their motor response is observed.

Mirror neurons appear to form a cortical system that matches observation and execution of motor actions. What may be the functional role of this matching system? Primates are usually in mutual relationship with conspecifics, living in groups characterized by several active and intense social interactions. It is therefore very important for each member of a given social group to be able to "understand" the meaning of the actions performed by conspecifics in order to appropiately react to it. The matching system represented by mirror neurons could provide the neuronal basis for such a process of "action understanding". Meaning would be assigned to the observed actions by matching them on the same neuronal machinery that generates them.

Brain imaging and TMS experiments provided evidence that an action/observation matching system, similar to that discovered in monkeys, does exist also in humans. The problem of the possible homologies between Broca's region and the premotor areaF5 of the monkey will be addressed.

The discovery of mirror neurons may provide a new, altough still sketchy, neurobiological basis to account for the emergence of language. This assumption will be discussed in relation with the following premises: a) Language skill has emerged through evolution by means of a process of preadaptation: specific behaviors and the nervous structures supporting them, originally selected for other purposes, acquire new functions that side and eventually superseed the previous one. b) A continuity can be traced between language skill and pre-language brachio-manual behaviors, being the primate premotor cortex the common playground of this evolutionary continuity; c) The specialization for language of human Broca's region derives from an ancient mechanism, the mirror system, originally devised for action understanding.


02.01-- Abstract No:1288

Is a real psychoscope possible? Inferring when brain images involve conscious experiences.

B.J.Baars (The Wright Institute, 2728 Durant Avenue, Berkeley, CA 94704, USA<baars@cogsci.berkeley.edu>)

Philosophers have suggested a science-fiction fantasy of actually gazing into someone else's private experience, by means of a "psychoscope." Rapid new developments in brain monitoring techniques take a step toward making that fantasy very real, by showing us neural processes as they take place in the living brain. But can we tell when a "hot spot" on a brain scan reflects a conscious neural event? This paper argues that we can, using convergent measures. A set of criteria is proposed for locating conscious and unconscious activities in the living brain. The criteria are applied to speech and visual brain scans, and single-cell recording methods. It appears that we may be within reach of a genuine psychoscope. This awe-inspiring possibility suggests a need to start thinking of the ethical as well as the philosophical and scientific implications of the new technology.


02.01-- Abstract No:1318

Beyond pandemonium: the role of the reticular core in unifying the stream of consciousness

J.B.Newman (Colorado Neurological Institute<newmanjb@aol.com>)

There has been considerable discussion recently about the possible role of coherent oscillatory activity in thalamo-cortical loops serving as a neural correlate of consciousness. Recent experimental evidence points to the importance of 40-Hz oscillations in temporal binding, while suggesting some limitations of the orignial "40-Hz Hypothesis". "Beyond Pandemonium" will trace progress in mapping conscious functions onto large-scale neural systems involved in perception, memory, emotion and volition, in the context of the evolving model of an Extended Reticular-Thalamic Activation System (ERTAS) of Newman and Baars.


See also:


Vision

02.02-- Abstract No:789

Modeling stimulus-driven selective visual attention using thalamorcortical and intrathalamic cell properties and connectivities

J.Bickle (Focused Research Program in Computational Neuroscience, Brewster A-327, East Carolina University, Greenville, NC 27858-4353, USA<bicklej@mail.ecu.edu>) , M.Bernstein, M.HeatleyG.Boyd, C.Worley, <>

Using software for implementing interactive activation and competition (IAC) parallel networks in computer simulations, we have modeled an intriguing neural mechanism for 'nonvoluntary, ' stimulus-driven selective visual attention. An IAC network contains segregated pools of units with bi-directional excitatory connections between units across pools and inhibitory connections within pools. The thalamic lateral geniculate nucleus (LGN) -thalamic reticular nucleus (RN) -primary visual cortex (V1) system exhibits similar connectivities. Relay neurons in LGN, which receive input directly from retinal ganglion cells, project excitatory connections to V1. V1 neurons send feedback fibers to LGN that obey a 'principle of reciprocity' so precise that corticothalamic (feedback) projections can be used to map thalamocortical (feedforward) projections. Both LGN feedforward and V1 feedback axons project collaterals to thalamic RN. RN projects only within the thalamus. These intrathalamic projections are inhibitory. (Virtually all are GABAergic.)

Our computer simulation contains 60 thalamic projection column (TPC) units and 12 cortical vertical column (CVC) units. A TPC unit has an excitatory bi-directional connection with a CVC unit just in case the receptive field of the TPC unit (a point of light in the simulated visual field) overlaps with the receptive field of the CVc unit (a bar of light at a particular location and orientation) . All TPC units have inhibitory connections with all others, simulating the effects of the RN-LGN circuits. We use CVC unit activation as a measure of attention to visual stimuli across the simulated visual field. After only a few processing cycles (<5) , activity in the CVC units whose receptive fields include the strongest stimulus is significantly greater than activity in CVC units whose receptive fields include even moderately strong stimuli. This enhanced activity resulting from the thalamocorticothalamic system enables higher areas of visual streams to process--attend to--stronger stimuli at the expense of weaker ones. We hypothesize that a large amount of nonvoluntary, stimulus-driven selective attention results from the cell properties and connectivities at subcortical and the earliest stage of cortical visual processing.

Using Genesis, a popular program for simulating biologically plausible network architectures on digital computers, we are now extending this basic model to include the effects of a fovea. We are also exploring different values for the input parameter processing variables. Preliminary work suggests processing times in line with temporal limits on the number of cycles through the thalamocorticothalamic system imposed by the actual circuitry of the primate visual projection system and behavioral parameters (e.g., saccade latency) . This is in line with our commitment to computational neuroscience and biological modeling, as opposed to abstract network modeling. We are also exploring the neural mechanism modeled here as an explanation of some data reported recently by Jack Gallant and David van Essen on firing patterns in V1 in monkeys exploring natural scenes.


02.02-- Abstract No:790

Modeling a voluntary selective visual attention mechanism using parieto-frontal cell properties and connectivities

J.Bickle (Focused Research Program in Computational Neuroscience. Brewster A-327. East Carolina University, Greenville, NC 27858-4353, USA<bicklej@mail.ecu.edu>) , M.Bernstein

Vision provides an excellent sensory modality for exploring mechanisms of selective attention using neural network computer simulations. The task in this study involves our capacity to voluntarily redirect attention to a portion of visual space after a strong distracting peripheral stimulus. This capacity is voluntary because it is independent of stimulus intensity and variably activated. There may be no salient stimulus in the area of visual space to which attention is redirected while the peripheral distraction remains strong. On some occasions we immediately redirect attention, while on others we explore the peripheral stimulus and then either redirect or establish a new fixation point for subsequent attention.

In tasks like this, the control of visual attention is the control of saccadic eye movements. Cortically, the frontal eye fields (FEFs) of premotor cortex and the lateral intraparietal area (LIP) of posterior parietal cortex are part of this control system. During the past decade, electrophysiological recordings from single neurons in these areas reveal both presaccadic and postsaccadic activity coded in oculomotor, rather than retinal, coordinates. LIP projects to FEF and receives extensive feedback projections. Both LIP and FEF project to intermediate layers of superior colliculi, which in turn projects directly to burst circuits in brain stem saccade generators.

Using Genesis, a popular program for implementing biologically plausible networks on digital computers, we have incorporated these findings into a neural network capable of redirecting attention to an initial fixation point after a strong distracting peripheral stimulus. Pre- and postsaccadic activity in simulated FEF and LIP circuits provide input to a vector subtraction mechanism that computes the next appropriate saccade during a sequence of eye movements from an initial fixation point. Our model suggests an intriguing mechanism for the decision to redirect or continue exploring the peripheral stimulus, based on a variable threshold on the 'redirect' input to the vector subtractor. When the threshold is set low, the redirect message is activated by a single postsaccadic signal. When the threshold is set higher, it takes a number of postsaccadic signals to activate it. Recent electrophysiological discoveries by Douglas Burman and Charles Bruce of saccade suppression cells in FEF provide an intriguing biological interpretation for the hypothetical 'redirect' message. Future work with this model will explore biologically plausible mechanisms for the variable control of the redirect threshold, and will introduce other connectivities (with angle of gaze sensors, with limbic cortex) that give LIP cells some special capacities. Using resources of computational neuroscience and biological modeling based on actual cell properties and anatomical connections, we are here hypothesizing nothing less than a biologically plausible neural mechanism for the 'voluntary control of attention.'


02.02-- Abstract No:1030

A biologically inspired connectionist architecture of the retina and thalamocortical system

D.Enke (Smart Engineering Systems Lab, University of Missouri - Rolla, 236 Engineering Management Rolla, MO 65409-0370, USA<denke@umr.edu>)

Numerous models of the primate biological vision system have been developed, although most are based solely on the visual cortex, with the processing occurring in a feedforward, hierarchical manner. Feedback connections between cortical areas, and the modeling of non-cortical areas such as the retina, lateral geniculate nucleus (LGN) , and pulvinar, are often overlooked. By developing neural models of these neglected areas, and adding bidirectional connections within and between these networks and other models of the visual cortex, it is possible to initiate individual visual processing characteristics while incorporating global processes, such as attention, into existing connectionist based vision models.

As an example, various types of neurons and bidirectional connections exist within the retina to perform a unique spatial and temporal processing of the input image. By utilizing a static version of the popular shunting networks for modeling the bipolar and ganglion cells, one that ignores motion information but highlights the spatial aspects of the image, it is possible to generate a spatial frequency filtered signal similar to the difference-of-gaussian profile produced by these cells. Additional filtering, noise reduction, contrast enhancement, and gain control can also be performed by making assumptions about more speculative processes, such as the potential role of photoreceptor blurring and amacrine cell function. Also, simple integrate-and-fire neurons can be used for the remaining cells in the retina network architecture since the desired network response characteristics are produced by the physical bidirectional connections between the neuron models.

In addition to the retina, this same network philosophy can be extended to the modeling of the thalamocortical system. By modeling the feedback interactions from the primary visual cortex to the LGN, including the lateral inhibitory and excitatory connections known to exist within the visual cortex, certain perceptual effects, such as feature completion, receptive field modification under the influence of surrounding context, and the enhancement of figure from ground, can be observed for objects within the visual field. In addition, if the competitive interactions of the neurons in area IT and the pulvinar are modeled, along with connections to and from the pulvinar nucleus and each of the modeled cortical areas, it is possible to fix a window of attention around specific objects, with the pulvinar signals affecting the gating of signals from the lower to higher visual areas. Also, by providing top-down matching signals from a higher cortical area (such as the inferior temporal cortex, posterior parietal, or frontal regions) , the network can locate and maintain attention on a specific object for extended periods.

After a brief review of the physiology involved, a network model of the aforementioned neural interactions will be presented, followed by demonstrations of its performance. A discussion of the resulting model's ability and significance for generating and explaining aspects of visual awareness, attention, and consciousness, will also be presented.


02.02-- Abstract No:1153

Nonhomogeneities in visual evoked potentials identifies thalamic gating demonstrating parallel processing that occurs during different levels of attention in man

J.H.Dougherty (Cole Neuroscience Center, University Of Tennessee Medical Center, Knoxville, Tennessee, USA) , S.E.Leppanen, M.L.Eisenatadt, , <>

Introduction: Conventional averaging of visual evoked potentials measures summated serial and parallel processing of visual signals. These averaging techniques cannot detect changes In the subject's internal state (level of attention) . The thalamic reticular nuclei control the gating and processing of visual signals between the arousal and attention systems of the brain. The objective of this study was to determine if the sorting signal classification technique could detect the presence of this thalamic gating mechanism.

Methods: Pattern reversal visual evoked potentials were recorded in 6 normal adult subjects (3 male, 3 female, mean age; 35.6, range: 25-50) . Subjects were tested twice during the same time of the day, 7 days apart. 0 250 epoches were recorded from MO-MF, MO-A1A2, RO-MF and LO-MF with 0.1 - 250 Hz filters, at 0.5 Hz with a time base of 300 milliseconds. Single epoches were stored off-line and subjected to the single sweep sorting with no training data analysis procedure. Amplitude histograms at each point in time were calculated across all 2501 epoches. Points of increased variability and homogeneous subaverages were calculated. Nonhomogeneities were identified by calculation of the standard deviation, skewness and kurtosis factors and the chi-squared goodness-of-fit of the amplitude histograms at each point. Non-Gaussian histogram density functions were used to sort indIvidual epoches into stationary subaverages.

Results: increased variability occurred with a mean of 124.5 milliseconds. Two stationary subaverages were calculated. The shorter latency subaverages had N7S, Pl00 and N145 components present with a mean PlOD latency of 100.5 milliseconds. The N145 component was present with a mean latency of 141.4 milliseconds and the N75 mean latency was 77.1 milliseconds. The shorter latency aubaverages N75 component was absent. The mean Pl00 component latency was 116.4 milliseconds and the mean N145 latency was 162.1 milliseconds. The epoches contributing to the shorter latency subaverages occurred earlier during the stimulation procedure and the epoches contrIbuting to the longer latency subaverage occurred later during the stimulation procedure. All changes in signal variability were reproducible from one stimulus session to the next.

Conclusions: The shorter latency subaverages with the N75 component present would be consistent with trnnsmission through the faster conducting retinogeniculocortical pathway. The longer latency subaverage with the absence of the N75 component would be consistent with transmission through the slower conducting extrageniculate pathways. The single sweep sorting analysis procedure is able to detect switching from one pathway to the other. This switchIng would be consistent with the Skinner-Yingling (Prog. Clin. Neurophysiol. 1977: 30-69) model for thalamic gating of sensory signals which regulates the level of attention in the brain. Application of this technique may aide in understanding of the mechanisms controlling attentIon in a variety of clinical problems. The technique will be applied to a larger group of subjects.


02.02-- Abstract No:1181

Visual awareness and the frontal lobes

C.Koch (Computation and Neural Systems Program, 139-74 Caltech, Pasadena, CA 91125, USA<koch@klab.caltech.edu>)

We (Crick and Koch, 1995) have hypothesized that the function of visual awareness is to produce the best current interpretation of the visual scene, in the light of past experience, and to make it available, for a sufficient time, to the parts of the brain that contemplate, plan and execute voluntary motor outputs. This suggest that the neurons that express the neural correlate of consciousness (NCC) must project from visual cortices to the frontal lobe, and in particular to prefrontal cortex.

We therefore predict that patients unfortunate enough to have lost their entire prefrontal cortex on both sides (including Broca's area) would not be visually conscious, although they might still have well-preserved, but unconscious, visual-motor abilities. No such patient is known to us (not even Brickner's famous patient) . The visual abilities of any such "frontal lobe" patient needs to be carefully evaluated using a battery of appropriate psychophysical tests. The fMRI study of the blindsight patient G.Y. (Sahraie et al., 1997) provides direct evidence for our view by revealing that prefrontal areas 46 and 47 are active when G.Y. is visually aware of a moving stimulus, but not when he is performing in his blind-sight mode. Large-scale lesion experiments carried out in the monkey suggest that the absence of frontal lobes leads to complete blindness (Nakamura and Mishkin, 1980, 1986) . One would hope that future monkey experiments reversibly inactivate specific prefrontal areas and demonstrate the specific loss of abilities linked to visual perception while visual-motor behaviors -- mediated by the on-line system -- remain intact. It will be important to study the pattern of connections between the highest levels of the visual hierarchy -- such as inferotemporal cortex -- and premotor and prefrontal cortex.

Our hypothesis, combined with the neuroanatomy of the macaque monkey, suggests that primates are not directly aware of neural activity in primary visual cortex, although they may be aware of such activity in extrastriate cortical areas. I will discuss much recent electrophysiological, psychophysical and clinical evidence that supports this hypothesis.

Finally, it is likely that the NCC neurons are a specific and identifiable subset of cortical/thalamic neurons with unique anatomical, biophysical or other properties. I will discuss the type of experiments --- drawing upon technical advances in molecular biology--- that will be necessary to address these problems experimentally in the foreseeable future.


02.02-- Abstract No:1285

Unconscious visual processing for action: evidence from normal observers

M.Goodale (Department of Psychology, University of Western Ontario, Canada)

Sight is our pre-eminent sense and the world of objects and events beyond our bodies is synonymous with conscious visual experience. We do not simply respond to visual stimuli; we experience them as integral components of a visual world that has depth, substance, and most important of all, an existence separate from ourselves. But even though the perceptual representation of objects and events in the world is an important function of vision, it should not be forgotten that vision evolved, not to provide perception of the world per se, but to provide distal sensory control of the many different movements that organisms make. In humans and other primates, it is becoming increasingly clear that the visual control of skilled actions functions quite independently from the visual processing leading to perception-based knowledge of the world. Evidence from both neurological patients and normal observers suggests that many of our actions are controlled by visual inputs that are quite inaccessible to conscious experience. In the normal observer, for example, the visual control of a number of different skilled actions has be shown to be quite insensitive to pictorial illusions and other displays that can have profound effects on conscious perceptual judgements. These and other demonstrations suggest that the visual control of many of our movements, from grasping objects to walking through cluttered environments, uses metrics that are quite different from those employed by conscious vision. It is as though there is a zombie within us -- a dedicated but quite unconscious computational system -- that programs and executes goal-directed actions on our behalf once we have identified the goal and the specific action we intend to perform.


02.02-- Abstract No:1286

On the neural basis of visual awareness

M.Mishkin (Department of Neuropsychology, NIMH/NIH)

It was recently proposed (Crick and Koch, 1995 Nature) that visual awareness depends on the interaction between higher visual cortical areas and prefrontal and premotor areas. This dependency was postulated on the assumption that visual awareness requires "reportability" of the activated set of visual neurons and, hence, a direct connection between those visual neurons and motor-related frontal cortex. This proposal is consistent with a finding (Nakamura and Mishkin, 1986 Exp Brain Res) that monkeys that had one hemisphere visually deafferented, by transection of one optic tract combined with forebrain commissurotomy, were subsequently rendered chronically blind when their visually intact hemisphere was subjected to a removal that included all of the cortex outside of the occipitotemporal, or ventral, visual processing stream. However, whether the chronic blindness is attributable specifically to the frontal-lobe portion of that extensive removal is still unknown. Another possible interpretation is that the blindness resulted instead from removal of the cortical polysensory areas, which may mediate interaction between the ventral visual processing stream and motor neurons at any of several levels of the nervous system, including but not restricted to the cortex. This interpretation was suggested by a follow-up finding indicating that unilateral removals limited to several putative polysensory areas produced much longer-lasting blindness than did unilateral removals limited to either the sensorimotor cortex or the limbic lobe, all three of these cortical divisions having been included in the original, extensive, removal. In none of the three partial removals, however, were the prefrontal and premotor areas ablated in full. Consequently, a choice between the two different proposals regarding the cause of the blindness, and, by implication, the neural basis of visual awareness, must await a direct comparison between the effects of the polysensory lesion and the effects of a combined prefrontal/premotor ablation. A study aimed at making this comparison is underway.


02.02-- Abstract No:1306

Unconscious visual processing for action: neuropsychological evidence

D.Milner (School of Psychology, University of St. Andrews, UK)

A number of experimental studies have been undertaken in which the visual perception of object properties is contrasted with the visual control of manual actions with respect to those same object properties. These methods have been applied to a range of individuals who have acquired different forms of impaired visual perception as a result of brain damage. This corpus of work shows that people can suffer severe loss or distortion of their perceptual experience of objects, while still retaining good visuomotor control with respect to those same objects. Examples will be given of research carried out with patients suffering from visual form agnosia, hemianopia, and unilateral spatial neglect.

The results of these studies will be interpreted as reflecting the operation of parallel brain systems for visual perception and visuomotor control. It will be pointed out in support of this view that the visuomotor systems in the brain can themselves be selectively damaged, causing a pattern of visual impairment that is opposite to that seen in (for example) visual form agnosia. In these patients the perception of object properties may be largely preserved while visuomotor control is poor.

It seems clear from these studies that brain damage can preclude conscious perception without seriously impairing visuomotor control. In other words, it appears that successful visuomotor control does not require visual awareness. It is therefore quite possible that, despite our introspective beliefs, the visual information that normally governs our actions “on line” is not present in our visual consciousness.


See also:


Other sensory modalities

02.03-- Abstract No:750

Neural basis of selective auditory attention in a gleaning bat, Antrozous Pallidus

K.R.Abdulrazak (Department of Zoology and Physiology, University of Wyoming, Box 3166, Biological Science 428, Laramie, WY 82071, USA<khalee@uwyo.edu>)

Selective attention is one of the vital components of decision making. The responses of neurons in the auditory cortex of the pallid bat show interesting properties that may subserve selective auditory attention. These neurons exhibit bimodal tuning and context dependent changes in response properties. At the lower end of the spectrum, they are selective for frequencies present in prey-generated sound, while being selective for their biosonar signals at higher frequencies. When presented with dichotic stimuli, these neurons appear monaural for biosonar pulses, but appear binaurally inhibited for prey-generated sounds. Context dependent changes in binaural properties of cortical neurons complement peripheral adaptations for spatial selection in this species. These results suggest convergence of two functionally and anatomically segregated pathways from the inferior colliculus onto cortical neurons. The use of a cortical sensory map for multiple functions is exemplified by this system. The unique response properties of the pallid bat cortex suggest that its auditory system uses a mechanism of selective attention that is based on cortical maps performing multiple functions. Information about the neural basis of selective auditory attention is sparse due to the lack of an animal model. Based on the electrophysiological data from the cortex, the feasibility of using the pallid bat as a model to study neural correlates of selective attention is discussed.


02.03-- Abstract No:1090

Consciousness, the Tomatis method, and the ear

B.Thompson (Listening & Learning/Tomatis Center, 2701 E. Camelback, Suite 205, Phoenix, AZ 85016, USA<drbthmpsn@aol.com>) , S.Andrews<75551.446@CompuServe.com>, , , <>

The Tomatis Method seeks to acknowledge the role of the ear in developing consciousness. It affects the body and mind through the entryway of the ear. This innovative program of sound stimulation, audio-vocal activities, and consultation helps us change our experience so that we can listen optimally both with our ear and our whole body. It was developed by Dr. Alfred Tomatis, French ear, nose, throat specialist and psychologist, who researched the improvement of listening, language, and learning as his lifelong work. The Tomatis Method is now used in over 200 centers worldwide and is rapidly expanding. The evolution of the method touches on philosophy, neuroscience, cognitive science and psychology, physical and biological sciences, and experiential approaches. It is an integrated, holistic approach to developing ones potential and achieving goals at an accelerated rate for people of all ages.

Connecting with our rhythms and those of others and our universe depends greatly on how well our auditory/vestibular system functions, on how well we listen with all our senses and integrate that information into our being. The Tomatis Method can be a valuable tool in furthering our consciousness through developing awareness of our personal existence, sensations, and thoughts within our environment. It can improve our ability to distinguish, process, and integrate incoming information. It can improve also our desire and ability to express ourselves. These connections are based in neuro-physiology and neuro-psychology.

Our ears link us one to the other and help us transform our views from one moment to the next. It is out of the vestibular system that the central nervous system evolves in the fetus. It is the auditory nerves which arethe first ones to fully be functioning in the fetus, thereby stimulating and charging the brain from halfway through fetal gestation. And as our whole body listens, it is sound which stimulates the movement of bubbles of consciousness within the microtubules of cells.

Many and varied kinds of changes occur in people who experience the Tomatis Method. Some seem even miraculous, while others notice a gradual improvement. Applications range from developing speech in autistic children to improving the learning and focusing skills of people diagnosed with ADD/ADHD, dyslexia, and learning disabilities to improving the voices of professional singers and actors. An entire application exists for training people to integrate the sounds of a foreign language so they can perceive its unique rhythm and frequecy range emphasis.

By education or re-educating the ear, the Tomatis Method can correct problems or enhance abilities. In addition, it can accelerate the rate of change effected by other modalities. The two presenters will present both a clinical and educational view of the background and use of the Method over the last ten years in the US with emphasis on a few case studies and evolving research.


02.03-- Abstract No:1094

A constructivist approach to pain perception

Y.Nakamura (Box 356540, Seattle, WA 98195-6540, USA<yoshio@accessone.com>) , C.R.Chapman<crc@u.washington.edu>, , , <>

As we collectively unravel the mystery of consciousness, some of us need to follow the thread of pain. This presentation will outline a constructivist approach to consciousness to understand how pain emerges out of multifocal distributed processing in the brain. By definition, pain is a phenomenon of consciousness. The standard scientific definition is: "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage". Pain research, which has concerned itself largely with information transmission and modulation, has difficulty addressing altered pain perception that does not derive directly from sensory neuromodulation. Consequently, pain research has not traditionally tackled the problem of consciousness in evaluating models of pain and its modification.

Recent brain imaging studies demonstrate that the brain manifests widespread distributed metabolic activity in the lenticular nucleus (internal capsule) , anterior cingulate, insular cortex, cerebellum, thalamus, somatosensory cortex, and superior and inferior frontal cortex, during the experience of pain as compared to a pain free state. This perplexes pain researchers because it is unclear which foci of activity produce the awareness of pain. Emerging research and theory on the mechanisms of consciousness, along with these brain imaging findings, suggest that a constructivist framework may bridge the gap that separates pain research and the study of consciousness and its alteration (e.g., hypnosis) . We propose that the brain constructs elements of pain experience (pain schema) and imbeds them in ongoing consciousness. Viewed in a constructivist framework, consciousness in general is an emergent property of a self-organizing process in a distributed neural network. The self-organizing process may act like a fundamentally Darwinian selection, involving a) the competition among multiple central response patterns for dominance, b) the integration of sensory input with other memory, various associations and motives appropriate to the immediate situation and the long-range goals of the individual, and c) the formation of a coherent whole from the sum of the many parts of the distributed processing. Once the contents of consciousness are dynamically constructed out of activated schemata instantiated in large-scale parallel distributed networks, the contents of immediate consciousness feed back to nonconscious, parallel distributed processes to help shape the character of future moments of consciousness.

We illustrate this approach's utility, considering two examples: 1) mechanisms underlying hypnotic analgesia and 2) the formation and maintenance of chronic pain. Hypnosis can dramatically alter the perception of painful stimulation, but the mechanism remains an enigma. Hypnotic suggestion may interact with distributed pain processing through feedback mechanisms that prime associations and memories, shaping the formation of future experience. In some chronic pain patients, pain can emerge and persist or recur episodically for months or years without identifiable organic cause. We suggest that chronically persisting pain in these patients may result from the emergence of reverberating, stable distributed networks that sustain the representation of tissue trauma in consciousness. We conclude that there may be more to pain than the contents of consciousness and that pain is the product of substantial preconscious processing involved in the construction of consciousness.


See also:


Motor control

02.04-- Abstract No:925

Readiness potentials and conscious decisions preceding a voluntary movement

J.A.Trevena (Psychology Department, University of Otago, P O Box 56, DUNEDIN, New Zealand< judy.arnel@stonebow.otago.ac.nz>)

The movement-related cortical potential (MRCP) that precedes self-initiated voluntary hand movements was recorded from scalp electrodes, and compared with subjects reports of when they had made decisions about the movement. The results support previous findings that the MRCP begins before the time when subjects report having decided to initiate the movement (Libet, Gleason, Wright & Pearl, 1983; Keller & Heckhausen, 1990) . For the first time, we also measured the LRP prior to spontaneous self-initiated movements. The LRP is an indicator of hand-specific motor preparation, and represents the lateralisation of the main negative shift (MN) that was identified as the NS component of the MRCP and used as the marker for the onset of cortical activity by Libet et al. (1983) . We report the onset of the LRP, relative to the time of subjects conscious decisions to move.

In the experiment, subjects watched a "clock" with a rotating spot during each trial, and later reported where the spot had been when they had decided to tap the key, by indicating whether the decision had been made before or after an experimenter-controlled reference time. The temporal- order judgments were used to create psychometric functions showing the probability of "decision first" judgments as a function of reference time. Previous studies have found that the average time of a decision to move is around 200 msec before threshold EMG (Libet et al., 1983; Keller & Heckhausen, 1990) , but have not examined the width (DL) of the psychometric function. In the current Experiment 1, the median "decision to move" time over 12 subjects and both hands was 51 msec before the keypress, with a DL of 84 msec. In Experiment Two, subjects were allowed to choose which hand to move as well as when to move, and were asked to report the timing of one of these two decisions in each half of the experiment. The median time of the decision when to move was slightly earlier than the decision of which hand to move (-78 msec vs -37 msec, F1, 10 = 4.73, p<0.1) , although this result was complicated by an interaction with task order (F1, 10 = 12.3, p<0.01) , with a larger difference between the tasks which were performed first, and in which the second task had a median decision time of about -90 msec, for both decisions. The DL of 55 msec did not vary significantly across tasks.

Slow negative cortical waves typically begin 1 to 1.5 seconds prior to EMG onset (Deecke, Grozinger & Kornhuber, 1976) , but do not appear until 0.5 seconds before a completely spontaneous movement (Libet et al., 1983; Keller & Heckhausen, 1990) . The MRCPs in Experiments 1 & 2 of the current study were present from around 1.2 seconds before the hand movements, despite the fact that each movement was reported as being spontaneous (movements reported as preplanned were excluded from analysis).


See also:


Memory and learning

02.05-- Abstract No:1114

Neural correlates of working memory

M.Osaka (Dept. of Psychology, Osaka University of Foreign Studies, Osaka 562, Japan<osaka@post01.osaka-gaidai.ac.jp>), N.Osaka<osaka@post01.osaka-gaidai.ac.jp>

Working memory represents the immediate memory processes involved in the simultaneous storage and processing of information.In the working memory, the emphasis is on the efficiency of storing the partial product of comprehension for a limited period while processing the incoming information. Working memory associated with reading, listening, and visuo-spatial tasks was measured using SQUID-based magnetoencephalogram (MEG) and electroencephalogram (EEG) . A magnetic field was tended to change as working memory load increased and the peak alpha-wave frequency shifted to higher frequency region when subjects engaged in the arithmetic and visuo-spatial cognitive task. The results indicate the peak alpha-wave frequency of the brain has close relation to working memory load.


02.05-- Abstract No:1193

The effects of adrenalin on memory

J.Cobb (655 University Avenue # C-5, Fairbanks, Alaska 99709, USA<ftjcc@aurora.alaska.edu>)

Studies have shown a positive correlation between activation of the limbic system thorugh adrenergic stimulation and facilitation of long-term memory formation. However, while small amounts can be beneficial to this end, too much adrenalin disables the process.


See also:


Neuropsychology and neuropathology

02.06-- Abstract No:873

A two dimensional model for psychophysiological categorization of predatory psychopaths

J.E.Alexander (Department of Psychology, Western Oregon University, Monmouth, OR 97361, USA<alexanj@wou.edu>)

Previous studies have produced inconsistent results regarding correlates between psychopaths and aspects of neurocognition. Part of this research problem undoubtedly revolves around identifying who qualifies as a psychopath. The present study presents a two dimensional model based on laboratory analysis of criminals brain activity and their individual levels of brain damage. Psychophysiological measures (EEG and ERP) and behavioral evaluation of events prior to and surrounding their crimes were utilized to create such a model. The data from these measures indicated two dimensions across which subjects consistently varied. These two dimensions were speed of sensory processing in the brain (measured using psychophysiological methods) and degree of reported damage to the brain. Categorization of subjects according to these two dimensions show a linear trend such that a majority of the subjects are either fast processing with no damage or slow processing with damage. This is intuitively obvious, however, there are some subjects with slow processing and no known damage and some with fast processing and history of damage. Thus, there is the need for a categorization method that measures each dimension separately. Of particular interest is that a subgroup of these subjects killed in a predatory manner whereas the remaining subjects killed due to varying situational circumstances. The predatory psychopaths consistently scored in the quadrant that indicated fast sensory processing and no brain damage. These results indicate that careful delineation of subgroups within the criminal populations may be made based upon psychophysiolgical aspects of their brain activity. Moreover, the behavior exhibited by these individuals is hard to explain from only a biological deterministic point of view given that normal individuals often have fast sensory processing without brain damage. Therefore, other cognitive and psychological influences on the individuals conscious state must be considered with regard to this extremely aberrant behavior.


02.06-- Abstract No:877

Developmental disturbances in the prefrontal neuronal network and its relevance to schizophrenia

K.Vogeley (Department of Psychiatry, Sigmund-Freud-Str. 25, 53105 Bonn, FRG< vogeley@uni-bonn.de>) , Y.Kawasaki, V.JungK.Zilles, B.Bogerts, P.Falkai<>

Among the basic principles in neocortical organization are functional segregation in unimodal association cortex areas and re-integration in heteromodal association cortex areas. The prefrontal cortex is the part of the heteromodal association cortex, to which all different unimodal association cortex areas in the parietal, temporal and occipital lobes converge, anatomically and functionally. By this re-integration mechanism the internal representation of a supramodal world model in our brain appears to be constituted. Additionally, the prefrontal cortex is the strongest candidate for the neuronal implementation site of the self model. This is suggested by close anatomical connections to the limbic system and by functional imaging and neuropsychological studies, which reveal that self-monitoring capacities are implemented in the prefrontal cortex. Such self-monitoring capacities are massively disturbed in schizophrenics as in such typical phenomena like hallucinations or delusions (Frith 1993) . This is the rationale for macro- and microscopic post mortem research on the prefrontal cortex of schizophrenic brains with special interest in neuronal network changes therein. Therefore, we performed a combined macro- and microanatomic study on the frontal lobe of 25 schizophrenic brains compared to age- and sex-matched control subjects. The volume of the frontal lobe was studied by planimetric analysis. Volumetric data revealed a statistically significant bilateral volume loss of the frontal lobe in male schizophrenics compared to controls (right: -35%, p = 0, 026, left: -41%, p = 0, 007) . Volume loss in male schizophrenics was due to a decrease in length of the frontal lobe. There was no significant volume change in female schizophrenics (right: +6%, left: +16%) . Additionally, the gyrification index as ratio of inner and outer contour (Zilles et al. 1988) was measured bilaterally in six different slices in all brains by automatized image analysis. Data were statistically worked up using MANOVA. The gyrification index revealed a significant change in the right frontal lobe in male schizophrenics in the area of right frontal pole as compared to control brains (p = 0, 024) . Gyrification measurements did not reveal any significant change elsewhere. Additionally, a microscopic study on cytoarchitectonic features of Brodmann area 10 belonging to the dorsolateral prefrontal cortex was performed and revealed a statistically significant decrease in cell density on the right side of the frontal lobe of schizophrenics compared to controls. As the gross macroscopic development of the frontal lobe including gyrification and neuronal migration to the cortex is completed during fetal life, its examination provide considerable information on early brain development. Changes in the development of the brains predisposing to schizophrenia strongly support the thesis of a neurodevelopmental origin of schizophrenia. Thus, the hypothesis of self model implementation in the prefrontal cortex is supported by psychiatric brain research in the pathological condition of schizophrenia.


02.06-- Abstract No:879

How dementia, dreaming and drugs [hallucinogenic and anaesthetic] implicate acetylcholine in the neurochemistry of consciousness

E.K.Perry (Medical Research Council Neurochemical Pathology Unit, Newcastle General Hospital, Westgate Road, Newcastle upon Tyne NE4 6BE, UK<e.k.perry@ncl.ac.uk>) , M.Walker, R.H.Perry, , <>

Naturally occurring anticholinergic drugs such as atropine and scopolamine have been used for centuries to alter consciousness -- ritualistically to induce hallucinations and medically to abolish conscious awareness during surgery. Contemporary views of the function of acetylcholine in the brain include, in the cortex, a role in selective attention and, in the brainstem and thalamus, control of cortical activation during awake and REM sleep cycles.

A wealth of information is available on how cholinergic systems are affected in degenerative diseases involving altered consciousness and cognition. In Alzheimer's disease loss of explicit more than implicit memory can be related to extensive cholinergic deficits in limbic areas such as the hippocampus. In Dementia with Lewy bodies (DLB) , the second most prevalent dementing disorder in the elderly, visual hallucinations which occur in over 80% of patients have been related to extensive neocortical deficits and relatively intact serotonergic activities. DLB is also characterised by fluctuations in consciousness and it remains to be established if abnormal cholinergic transmission, identified not only in the cerebral cortex but also in the ventral striatum or thalamus (particularly reticular nucleus) , is involved in this clinical characteristic.

Although REM abnormalities have been identified in AD and DLB, these have most consistently been reported in Parkinson's disease (PD) . Reductions in REM sleep density and duration in PD, together with preclinical REM behavioural disorder (abnormal motor activity during dream mentation) are likely to arise from brainstem pathology which includes loss of pedunculopontine cholinergic (together with noradrenergic and dopaminergic neurons) . Cholinergic therapy (systemic anti-cholinesterases) has recently been introduced for cognitive impairments associated with Alzheimer's and related diseases. Since muscarinic and nicotinic cholinergic receptors are widely distributed throughout the brain, effects of such drugs on conscious awareness, hallucinations or REM patterns may be worth monitoring.

Tacrine, the first cholinesterase inhibitor licensed for the treatment of Alzheimer's disease, was originally employed, decades earlier, for the reversal of delirium, associated with anticholinergic medication and to promote recovery of consciousness following anaesthesia. In modern anaesthesia antimuscarinic agents have been used to induce "twilight sleep", during which patients are awake but not aware of or able to remember the procedure. The CNS nicotinic receptor a4ß2 subtype has recently been implicated in the mechanism of action of volatile general anaesthetics. This receptor is more potently affected by eg isoflurane than the most sensitive GABAA or glycine receptor. Inhibition of the CNS nicotinic receptor together with potentiation of GABA and glycine receptors is thought to contribute to the efficacy of general anaesthetics.

These drug and disease related observations on acetylcholine indicate that this particular transmitter, the discovery of which followed a dream by Otto Loewi in 1922, is likely to be quite specifically involved in mechanisms of consciousness. Since the cholinergic input is considered to be the most important modulatory influence on the cerebral cortex and since amongst brainstem projections the cholinergic is the major input to the thalamus, acetylcholine may be involved in controlling both the content and intensity of the conscious stream.


02.06-- Abstract No:1049

Attentional cueing in blindsight

R.W.Kentridge (Psychology Dept., University of Durham, Durham, DH1 3LE, UK<robert.kentridge@durham.ac.uk>) , C.A.Heywood, L.Weiskrantz, , <>

Attention and awareness are intimately linked in a number of theories of consciousness. The relationship between them was investigated by examining the effects of three types of attentional cues on the response of the blindsight subject GY to stimuli (1 degree diameter discs with contrasts of -48% (condition 1) or -31% (conditions 2 and 3) presented for 0.6 seconds at coordinates (in degrees) of 1.56, 8.86 or 8.69, -2.33) in his 'blind' visual hemifield. In all the experiments described below GY very rarely reported any awareness of the target stimuli in his blind field about which the cues provided information. His task was to indicate as soon as possible after a signal tone whether or not a target had been presented at either of two locations. Analyses of covariance of mean reaction-times for each block of trials with a covariate of the measure of discrimination A' were used to take changes in speed-error trade-off into account when analysing the effect of cueing. Condition 1: Cues presented at GY's fovea (which is not blind) indicating the most probable of two possible locations at which a target would be subsequently presented in his blind field significantly decreased his reaction-time in comparison to cues providing incorrect information (F (1, 4) =18.32, p<0.05) . Condition 2: Cues presented in the blind field in the location at which a target was likely to be subsequently presented also decreased reaction-time in comparison to cues which preceded the presentation of a target in the other location (F (1, 9) =6.19, p<0.05) . This cue-advantage occurred for both very high contrast (-86%) cues of which GY often reported having some awareness (87% of trials where commentary keys were used) and for low contrast (-31%) cues of which he was more often unaware (40% of trials) (Cue-validity x Cue-contrast interaction F (1, 9) <1) . Condition 3: When a cue in his blind field indicated that a subsequent target was likely to be presented in the other location GY showed a reaction-time advantage (F (1, 19) =10.2, p<0.01) but this advantage depended on high cue-contrast (Cue-validity x Cue-contrast interaction F (1, 19) =6.52, p<0.05) . All three conditions provide evidence that GY can direct attention within his blind field. Condition 2 shows that attentional cueing is effective even when the subject is unaware of the cues themselves. The lack of cue-advantage for low contrast cues in condition 3, however, indicates that cueing without awareness is only effective in situations where the direction of attention is automatic, it is not possible to make use of non-conscious cues when applying a voluntary rule-based redirection of attention. The following conclusions can be drawn: The direction of attention to the spatial location of a stimulus is not sufficient for awareness of that stimulus. Awareness of a stimulus and direction of attention by that stimulus are dissociable. Awareness may be necessary for the voluntary direction of attention.


02.06-- Abstract No:1093

Words without thought and other fragments of behavior in chronically unconscious humans

N.Schiff (Department of Neurology and Neuroscience, New York Hospital-Cornell Medical Center, New York NY 10021, USA<nschiff@mail.med.cornell.edu>) , U.Ribary, F.Plum, R.Llinas

The vegetative state reflects the dissociation of brain arousal mechanisms from those more closely associated with consciousness. In this setting, the occasional appearance of fragments of apparently organized behavior and wakefulness, is a disturbing and potentially confounding observation. Given the challenge presented by these observations, we sought to understand the correlation of such expressed behavior and brain function. Meticulous examination and clinical characterization were implemented in five patients in a persistent vegetative state (range 6 months to 20 years). We correlated the results of functional brain imaging by magnetoencephalography (MEG), positron emission tomography (PET) and continuous video EEG monitoring with anatomical information obtained from magnetic resonance imaging (MRI). Three patients (1,2 and 3) showed dissociations between fractionally coordinated behaviors and quantitative brain function.

Patient 1 infrequently spoke single understandable words and demonstrated preserved islands of functional metabolism in the left hemisphere (frontal operculum and temporal-parietal cortex). High frequency components (gamma range) with partial reset were recorded with MEG during early sensory processing in the left hemisphere only. Patient 2 exhibited fragments of coordinated movement accompanied by globally reduced brain metabolism with a comparatively higher metabolism of frontal lobes (prefrontal cortex, orbital cortex and related subcortical structures). Patient 3 demonstrated during arousal, behavioral patterns of profound emotional-autonomic responses to somatosensory stimulation. MEG data indicated evidence of early and late sensory processing. Somatosensory stimulation induced normal contralateral reset synchronization responses. In response to auditory stimuli, a reset and coherent synchronized activity in the gamma range and abnormal later evoked field components were observed only within the right hemisphere. Baseline brain metabolism in this patient demonstrated a 60% reduction of global metabolism, consistent with previous PET results in vegetative patients. Patients 4 and 5 demonstrated unremarkable clinical presentations of the vegetative state. However, Patient 5 showed remarkable preservation of cortical metabolism, despite a primary injury of the mesencephalon bilaterally leading to degeneration of the mesothalamic connections and thalamus.

The findings suggest that, although global integration of modular functions characterizes the normal human brains, partially preserved and isolated modules of activity may be expressed by unconscious brains. Such modular activity may include functions such as spoken language (in the form of single words), or random coordinated movements. The preservation of high metabolic activity in large areas of cortex in a single patient with marked thalamic degeneration following complete loss of the ascending reticular formation emphasizes the crucial role of mesothalamic circuits in the organization of consciousness.


02.06-- Abstract No:1185

Human split brain and the unity of consciousness: A matter of content or a question of relevance?

D.Forest (Philosophy Dept., University of Lyons, 74 Rue Pasteur, 69 007 Lyons, France)

The psychological testing of commissurotomized patients has often led to hasty philosophical conclusions about the nature of consciousness. In fact, the well-known equation between split brain and split mind relies heavily upon tests of identification and comparison of visual data, and upon the associationist philosophy usually involved in the assessment of disconnection syndromes. But the discrepancy between the behavioural unity shown by the patients and the disunity of their perception remains a puzzling fact without any proper explanation, as long as the pervasive influence of the associationist way of thinking remains dominant and is never questioned in itself. In consequence, it is a philosophical task of some consequence to point out what the weaknesses of assoicationism really are, and what kind of alternative could lead to a better understanding of split brain phenomena.

If we believe, like the associationist does, that a complex idea is composed of simpler ones, then there is no reason why the patient could make (except by chance) a proper judgement on the nature of a given whole when he is deprived of a full and direct access to some part of this whole. But in certain cases, a complex idea (the idea of a pair of letters including at least one vowel, for instance) , refers to a specific kind of arrangement, but is not composed of the representation of any visual data as such. Consequently, conjecture about the nature of the whole may succeed where perception would have failed. If the split brain patient succeeds in integrative tasks which involve information about things he cannot identify, it is because the questions he is able to answer are related to the relevance of categories: they do not concern the content of the visual stimuli.

Another advantage of the distinction between consisting of and refering to is that, stressing the importance of the latter, if is no longer necessary to postulate in commissurotomy any convert or implicit knowledge about the visual data, which always brings back to the intricacies of unconscious representation theories. Accurate reference to something involves nothing but specific access to relevant, if partial, information.

Moreover, according to Justine Sergent (Brain, 1986, 1987, 1990) , the filtering of information through the subcortical structures is sensitive to the nature of the information itself. What is of some importance for the guiding of action, the analysis of the exteroceptive field, the emotional reaction of the subject, is conveyed. What is not is the aesthetic part of the data, the details that are only secondary in practical perspective. Accordingly, there is no wonder that the integrity of consciousness can survive in most situations the unity of perception, such a unity being nothing in a sense but a kind of biological luxury.

The implications may be even wider. Complex ideas consisting of simpler ones are the product of a rather theoretically-oriented mind; relevant decisions refering to the ambiant world involve a different vision of consciousness. If the latter model prevails on the former, and if the normal brain's activity relies fundamentally on the same information processing mechanism as the divided one's several conclusions can be drawn. The integrity of consciousness is not equivalent to the omniscience of the self; representation should not be considered as the essence of consciousness; and speech is not in its main function the linking of an image and a name. Maurice Merleau-Ponty once wrote that consciousness is not fundamentally something like a 'I think that' but is rather a sort of 'I can'. Mutatis mutandis, this assertion may be as illuminating for today's cognitive psychology as it has been for the phenomenological research of the middle of this century.


02.06-- Abstract No:1211

What catatonia can tell us about the nature of consciousness: A neuropsychiatric approach

G.Northoff (Psychiatry, University of Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany)

INTRODUCTION: Neuropsychiatric disturbances may reveal psychophysical mechanisms of consciousness. A particular interesting in such a context is catatonia. Catatonia is a psychomotor syndrome where patients neither are able to move nor to speak while they experience intense and uncontrollable emotions (i.e. anxieties) . Furthermore they often show bizarre posturing of their extremities of which they are not aware of. Subsequently catatonia raises the question of the psychophysiological mechanisms of awareness and consciousness with regard to motor function.

METHODS: FIRST subjective experiences of catatonic patients were investigated with special emphasis on the awareness of their disturbed motor function and compared with those of parkinsonian patients who suffer from similar loss of movements. Therefore a special semi-quantitative self-questionnaire was developped for that purpose. SECOND the alterations of motor awareness in catatonia are theoretically be compared with other disturbances in the awareness and conscious perceptions of movements, especially the motor neglect. THIRD pathophysiological mechanisms of posturing as a non-awareness of the need of termination of movements are empirically investigated by means of the readiness potential.

RESULTS: FIRST, unlike parkinsonian patients, catatonic patients are not aware of their motor deficits. They often do not realize that they are completely immobile and show bizarre posturing. Instead they often experience intense and uncontrollable emotions which, as they describe it, block their movements and their will entirely. SECOND alterations in awareness of movements in catatonia cannot be entirely equated with other disturbances in motor awareness such as the motor neglect. Catatonic patients seem to suffer from a higher-order psychological dysfunction leading to a completely different kind of consciousness encomprising almost all psychological functions and not just only motor function as it is the case in the motor neglect. THIRD catatonic patients show major alterations in the readiness potential during posturing in frontal and parietal electrodes which is further supported by studies with SPECT and F-MRI.

CONCLUSIONS: FIRST similar to sensory modalities (for example: visual awareness and visual consiousness) there exists an awareness and consiousness of motor functions (and movements) which could be disturbed on different levels. Subsequently investigation of motor function could open an access to the study of the functional mechanisms of awareness and consciousness in the brain as well. SECOND taking account of catatonia one may distinguish between different levels of motor awareness, the higher-order forms probably leading to consiousness of movements. Subsequently these different levels, i.e. forms of awareness and consiousness of movements may be characterized by different neurophysiological mechanisms probably related with different brain areas and different forms of neural interactions. THIRD functions of higher-order awareness and concsiouness of movements may be physiologically characterized not only by the activity of one particular brain region but by means of distinct interactions between neural events taking place in different localisations of the brain. Subsequently future empirial investigations of awareness and consiousness of movements should rather focus on cortico-cortical functional connectivity than on the neural activity of just one particular cortical (or subcortical) area.


02.06-- Abstract No:1250

A case of deaf hearing related to central pontine myelinolysis and extrapontine lesions. Neuropsychological observations

M.Mozaz (Psicobiología. Procesos Básicos. Facultad de Psicología UPV. Apartado 1249 20080 San Sebastíán. Gipuzkoa. Spain.<pbpmogam@ss.ehu.es>) , A.Lopez de Munaín, J.Ruíz, , <>

Deaf Hearing occurs in patients which exhibit auditory responsive behavior without auditory awareness as a consequence of lesions in the auditory cerebral system. There are very few cases reported in the literature and there have not been extensively examined. Central pontine myelinolysis (CPM) with extrapontine lesions is also a rare condition characterize by spastic tetraparesia, pseudobulbar palsy and the "locked-in syndrome" and it is frequently fatal.

We report a case of a patient who developed evidence of clinical and Magnetic Resonance Imaging (MRI) of CPM and extrapontine lesions after correction of a profound hyponatremia. Our patient (IA) , a 26 year old right-handed woman developed a severe syndrome and coma which persisted for 6 weeks. After that time, she started to give evidence of improvement, clinically and in the MRI which still demonstrated pontine and extrapontine bitemporal cortical and subcortical lesions. Palpebral reflexes were preserved (100%) and the results in audiogram explained only a loss of 20% of hearing. Auditory evoked potentials correlated with bilateral damage to the pathway medial geniculate bodies-gyrus temporal.

The patient was mute and made no spontaneous effort to communicate. She apparently suffered a cortical deafness. Neuropsychological assessment was performed 14 weeks after the acute state. At first, she consistently denied hearing sounds which she had reacted to (although very slowly) , so, before the formal examination, we gave her several training sessions to help her became aware of her reaction and to discriminate between hearing and understanding. Formal examination included tests of verbal and written language comprehension, concept formation, executive functions, praxias, memory, psycho-acoustical functions and lip-reading.

The results of the neuropsychological examination will be reported. Scores on psycho-acoustical functions were very poor and inconsistent. Her partial hearing loss did not explain her initial pseudocortical deafness and her psycho-acoustical deficits. We suggest that IA´s initial pseudocortical deafness was probably the result of a combination of her initial deaf hearing, subsequent auditory inattention, which were overcome by training, and her very severe auditory agnosia.

We finally emphasize the need for a differential diagnosis in cases of cortical deafness and /or psycho-acoustical impairment. The ability of patients to reading lips will also have to be assessed -- to be used, if possible, as an effective approach to communicate with them. All together this would help to develop effective therapies in patients who suffer these kind of pathologies.


02.06-- Abstract No:1279

Blindsight and its neuronal basis

P.Stoerig (Institute of Physiological Psychology II, Heinrich-Heine-University, D-40225, Duesseldorf, Germany<petra.stoerig@UNI-DUESSELDORF.DE>), A.Cowey, R.Goebel,

Patients with partial cortical blindness that results from damage to part of the primary visual cortex may show a variety of reflexive as well as non-reflexive visual functions within the field defect. If the blindness is absolute, i.e. the patients do not consciously see the visual stimuli they still respond to, these functions are summarily termed Blindsight. Macaque monkeys with unilateral ablation of primary visual cortex exhibit similar residual visual functions. They can achieve up to 100 % correct detection of stimuli presented in the hemianopic field. Nevertheless they classify the same stimuli as blank trials in a signal detection task, and reaction time measurements indicate that they perform as if they were only guessing whether or not a target had been presented. These are hallmarks of blindsight - excellent function in the absence of both phenomenal vision ('I don't see it') and conscious access to the visual information ('I'm only guessing') . Physiological recordings in monkeys have shown that many cells in the extrastriate visual cortical areas that form the dorsal (occipito- parietal) stream remain visually responsive in the absence of primary visual cortex. This finding has suggested that it may be the lack of ventral (occipito-temporal) stream responsivity that results in the lack of conscious vision. However, with functional magnetic resonance imaging in patients with Blindsight we have not only confirmed that extrastriate visual cortex remains visually responsive, but that in addition to dorsal stream areas ipsilesional ventral stream areas retain visual responsivity. Blindsight therefore appears to be not an instance of solely sub-cortical or dorsal stream vision.


02.06-- Abstract No:1280

Using neural networks for discriminating functional connectivity in schizophrenia from normal connectivity

G.Josin (Department of Psychiatry, University of British Columbia 2255 Wesbrook Mall, Vancouver, B.C. Canada V6T 2A1<liddle@unixg.ubc.ca>) , P.F.Liddle

This work investigates the capability of neural networks linked in tandem with statistical techniques to distinguish large complex Positron Emission Tomography (PET) data sets of distributed cerebral function during tasks associated with particular brain processes implicated in schizophrenia. Neural networks are non-linear computational systems whose development was inspired by neurobiology. Their non-linear nature has allowed them to achieve success in modelling complex dynamic systems which were incapable of being satisfactorily modelled with traditional, linear methodologies, notably those based on statistical regression (Josin, G. (1988) Neural-Space Generalization of a Topological Transformation, Biological Cybernetics, 59: 283-290) . PET provides images of distributed cerebral activation, and can be used to map the patterns of functional connectivity during particular mental tasks. The neural network approach makes it possible to analyse and interpret the complex data sets of cerebral activations mapped by PET. It was our goal to develop a diagnostic system that can distinguish the patterns of cerebral activity occurring in schizophrenic patients and in healthy individuals. Disordered functional connectivity between left frontal cortex and sites including thalamus, temporal lobe and medial parietal cortex is characteristic of schizophrenia (Liddle P.F., et al. (1997) Schizophrenia Research 24; 168) . Regional cerebral blood flow (rCBF) was measured using PET during word generation in 17 schizophrenic patients and 6 healthy subjects, during 6 scans, in which the subjects were engaged in tasks that placed differing demands on the need to generate words. A covariance image was derived for each subject in which the value in each pixel represented the correlation between rCBF in that pixel and rCBF at a cardinal locus in the left lateral frontal cortex. A neural network was trained to distinguish covariance patterns in 6 patients from those 4 healthy subjects. When the test set subjects were tested blindly, the network successfully classified 92% of subjects. Our procedure may be useful for characterising distributed brain processes underlying conscious and unconscious cognition and affect.


See also: 02.06


Anesthesia

See:


Cellular and sub-neural processes

02.08-- Abstract No:1220

Decreasing of neuronal complexity in brain ischemia

Z.Budimlija (Institute of Forensic Science and *Department of Anatomy, Faculty of Medicine, University of Novi Sad, Hajduk Velkova 3, 21000 Novi Sad, FR Yugoslavia<zbuda@EUnet.yu>), G.Stojilkovic, M.Tasic, A.Polzovic

The basic concepts of fractal geometry hold that natural objects (including microscopic images) are not regular sets of points and cannot be described well enough using ideal constructions of Euclidean geometry. These facts have been used for developing methods for the "complexity measuring" of different natural shapes (cells, particles, geographical objects, etc) . The intent of this paper is to report the evidence that urkinje cells of the porcine cerebellum have a fractal nature, and that the fractal dimension, as quantitative measure of cell shape complexity, could serve as valid tool for the determination of their moorphological complexity, especially dendritic arborization. The fractal analysis of Purkinje cells from porcine cerebellar cortex in parasagittal plane was performed. For analysis there were used 9 blocks of porcine cerebellar tissue of both sexes, of the same age (6 months) and body weight (about 100 kg) . There were three different groups of animals: the control one, bledded by 20% of circulatory volume and bledded by 40% of circulatory volume. Pigs were sacrificed 4 hours after bleeding. Blocks of cerebellar tissue were prepared using Golgi stained echnique and cut in parasagittal anatomical planes. In the aim of cell shape analysis, the digitalization of icroscopic image was done. The box-counting fractal dimension (DB) was determined for each analyzed Purkinje cell using og-log plotting, in the aim of performing linear approximation of necessary numeric values by first degree polynoma. The average value of fractal dimension are: 1.7181 +/- 0.05 in the first group (control) , 1.56043 +/- 0.057 in the second group (20% bledded) and 1.36397 +/- 0.12 in the third group (40% bledded) . Obtained results are statistically different at the level of significance p=0.05. According to obtained results, the onclusion is that the fractal analysis is a powerful tool for complexity of neurons quantification and omparison, and the complexity of neuronal shape decreases with increasing level of brain hypoxia.


Quantum neurodynamics

02.09-- Abstract No:933

Locating the interface in a mixed quantum/classical model of brain function

S.Hagan ( 3-1-1 Kannondai, Tsukuba 305 Japan<scott@narc.affrc.go.jp>) , M.Hirafuji<masayuki@narc.affrc.go.jp>

Models of consciousness that invoke a quantum aspect allow puzzles, like the binding problem and the non-locality of memory, that persistently plague purely neural accounts to be realistically addressed but such models critically depend on the nature and efficacy of the interface with classical mechanisms of brain function. In order that theories of this kind can take any advantage of their dual nature, a bi-directional flow of information must first be facilitated. Such an interface is described in a theory of macroscopic quantum ordered states. It is our intention both to provide quantum signals with the means to influence meso-scale neural function and to elaborate a mechanism by which the discriminated information inhering in networks of neurons can be usefully translated into a quantum encoding. It is shown that the first objective can be achieved generically without the restrictive assumptions of previous models. Moreover the mechanism is relatively robust against environmental stresses, such as thermal noise, ambient electromagnetic radiation and ionic impurities. It is further demonstrated that a field theoretic formulation is resistant to the sort of objections that have justifiably been leveled against quantum mechanical approaches in the past. The propagation of information from the classical to the quantum system is treated in a model tracking the effect of modulating the membrane potential on the establishment and interaction of coherence domains. Empirically, the interface may provide the most promising site at which to observe the presence of a quantum component in the functioning of the brain.


02.09-- Abstract No:1078

Hierarchic model of consciousness

A.Kaivarainen (Department of Applied Mathematics and Cybernetics. Petrozavodsk state University, 185000, Petrozavodsk, Russia.<H2o@karelia.ru>)

Hierarchic Model of Consciousness (HMC) , proposed is based on original Hierarchic Concept of Matter and Field (Kaivarainen 1995; 1997) . This model is in fair accordance with some nontrivial results, obtained within Neurophone - the device, invented by P. Flanagan (P. Flanagan and Gael Flanagan, 1995; 1996) , making it possible the acoustic signals perception even for deaf people.

In accordance to HMC, each specific kind of neuron ensembles excitation corresponds to hierarchical system of three-dimensional (3D) standing waves of following types:

- thermal de Broglie waves produced by translations and librations of molecules;

- electromagnetic (IR) waves;

- acoustic waves;

- vibro-gravitational waves.

Such a hierarchic system of 24 collective excitations could be generated by quantum transitions of the coherent water clusters, localized in the microtubules of neuron bodies. These primary quantum excitations, representing coherent clusters (effectons) are resulted from high temperature molecular Bose-condensation of water. The correctness of this important statement is confirmed quantitatively by means of our theory based computer program: "Comprehensive Analyzer of Matter Properties, CAMP" (copyright 1997, A.Kaivarainen) . It is assumed in our model that collective bending or deassembly of big number of microtubules, induced by excitation and neuron's body depolarization is interrelated with its volume and shape ''pulsation''. The twisting of centrioles in cells to orientation, corresponding to maximum energy of the MTs distant interaction is an important stage of excited neurons dynamic adaptation.

As a result of cell's volume/shape pulsation, the distribution of synaptic contacts on the surface of cells and/or ionic channels activity change. These redistributions provide the long-term and short-term memory correspondingly. The processing of huge number of such ''informational acts'' in the head brain is responsible for consciousness and braining (Kaivarainen, 1996) .

The mechanism proposed needs the existence of feedback reaction between following stages of HMC:

a) simultaneous depolarization of big enough number of neurons, forming ensemble;

b) increasing the fraction of collective excitations in microtubule system of this ensemble, stimulating cavitational fluctuations in MTs due to piezoelectric perturbations of MTs structure; c) collective deassembly of MTs of big group of depolarized neurons due to their destabilization by Ca^+2 and resonant energy exchange between MTs by means of IR photons and vibro-gravitational waves;

d) simultaneous generation of nerve impulses (potentials of action) in axons of these cells - collective firing;

e) volume/shape pulsation of neuron's body and dendrites, inducing reorganization of ionic channels activity and that of synaptic contacts in the firing neuron ensembles.

Our model predicts that if the neurons or other cells, containing MTs, will be treated by acoustic or electromagnetic field with resonance frequency of internal MTs water cavitational fluctuation excitation of about 40 kHz, it can reduce the energetic threshold of simultaneous deassembly of big number of MTs, responsible for maintaining the specific cell volume and geometry. As a result, it activates the neuron's body volume/shape pulsation.

Such external stimulation of supercatastrophes has two important consequences: -the first one is generation of strong high-frequency nerve impulse, propagating via axons and exciting huge number of other nerve cells, i.e. stimulation of nerve signals transmission in living organism; -the second one is stimulation the leaning process as far long-term memory in accordance to HMC, is related to synaptic contacts reorganization, accompanied the neuron volume/shape pulsation.

The first of these two consequences of HMC is in accordance with phenomena of ''ultrasound hearing'', discovered by P. Flanagan and used in his ''Neurophone'' (Flanagan, 1996) . It consists of a (30-50) kHz amplitude modulated by ordinary acoustic waves ultrasonic oscillator that generated 3.000 volts peak across two insulated electrodes that were placed in contact with certain skin points. It was shown that the skin under the electrodes was caused to vibrate by the energy field with ultrasonic frequency. Even totally nerve-deaf people can hear with Neurophone.

The second mentioned above consequence of HMC is confirmed also by means of digital Neurophone version: Thinkman Model 50. It was demonstrated that if the educational tapes were played throw device, the information is very rapidly incorporated into long-term memory (Flanagan, 1996) . These data can be considered as an experimental proof of our Hierarchic Model of Consciousness.

REFERENCES:

Kaivarainen A. Hierarchic Concept of Matter and Field. Water, biosystems and elementary particles. (New York, NY, 1995, pp.485) ; the prospect of 2nd edition of this book and related papers see in URL: http://kftt.karelia.ru/~alexk

Kaivarainen A. Abstracts of conference: Toward a Science of Consciousness, Tucson, USA, p.74 (1996) .

Flanagan P. and Flanagan Crystal. The Neurophone. Earthpulse Flashpoints (Earthpulse Press, USA) , 1996, 1, 1-10; 1996, 3, 1-12.


02.09-- Abstract No:1267

Quantum modeling of spin wave-like collective states in brain cells

N.Markovska (Research Center for Energy and Informatics, Macedonian Academu of Sciences and Arts, P.O.Box 428, Skopje, Macedonia<natasa@manu.edu.mk>) , J.Pop-Jordanov, N.Pop-JordanovaE.A.Solov'ev, , <>

Recently the interest for investigation of highly complex brain functions as consciousness and memory, has been remarkably increased. This particularly holds for theoretical consideration of brain processes on sub-microscopic level in the framework of quantum brain dynamics. Within this concept, a new quantum model has been proposed, where elementary constituents of the brain (so-called corticons) exhibit coherent behavior, while the macroscopic observables, describing stationary and quasi-stationary states of the brain, are derived as dynamical output from their interaction with photons. Information printing is achieved under the action of external stimuli producing breakdown of the continuos symmetry associated to corticons. Ordering and coding are achieved by the condensation of collective modes in the vacuum, as the minimum energy state representing memory [1].

On the other hand, in the framework of our theoretical research on advanced methods for quantum modeling of thin films, some new specific quantum states have been revealed [2], with possible applications in the brain studies, combined with neurophychological and biofeedback techniques [3]. Along this line, a joint research program has been established dedicated to the investigation of physical phenomena underlying consciousness. It includes creation and annihilation dynamics of corticons (as energy quanta of the water rotational field extending to the whole assembly of brain cells in cerebral cortex) and photons (as energy quanta of the electromagnetic field) , within a more detailed quantum approach to collective modes of spin wave-like states of water molecules. As a first step, the theoretical considerations and numerical calculations of quantum spectrum will be related to a single rotator interacting with the external field. After proper interpretation of the characteristics of the quantum spectrum, the whole theory and calculations will be extended to collective mode of rotators with special attention on symmetry and the mechanism of symmetry-breaking. Some preliminary results will be presented in this paper.

[1] Jaby M., Yasue K., Quantum Brain Dynamics and Consciousness, John Benjamins Publishing Company, Amsterdam/Philadelphia, 1995.

[2] Markovska N., Pop-Jordanov J., Solov'ev E., Canalized States in a Two-dimensional Models of Thin Films, J. Phys. A. Math.Gen., 28, L201-L206, 1995; Markovska N., Pop-Jordanov J., Solov'ev E., Total Reflection and Canalized States in 3D Quantum Model of Thin Films, Physics Letters A 234, p. 251-261, 1997.

[3] Pop-Jordanova N., Boskovska V., EPI and EPQ: The Fuzzy Reasoning Expert Systems in the Pediatric Psychodiagnostic, Proc. Second Baltic Sea Conference on Phychosomatic Medicine, Ronneby, H.2, 1995; Pop-Jordanova N., Zorcec T., Demerdzieva A., Psychological Characteristics and Biofeedback Resilience..., Proc. IAAH Meeting, Lausanne, Sept. 1997.


02.09-- Abstract No:1305

Physics approaches to consciousness

K.Yasue (Research Institute for Informatics and Science, Notre Dame Seishin University, Japan)

Possible solutions to the easy and hard problems in consciousness study are given from the two modern physics approaches; realistic physics and fundamental physics, respectively. In the former approach, the easy problem can be solved within the framework of quantum field theory of macroscopic matter completed by Umezawa and Takahashi in the 1980s. Mind (or self) is a physical aggregate of the non-propagating evanescent light made of macroscopically condensed photons (light quanta) trapped in the vicinity of the biological constituent matter of the brain such as membranes, ordered water, cytoskeletal filaments and microtubules. Consciousness is the dynamics of those macroscopically condensed photons suffering from interactions with the external systems of the biological constituent matter, and described by the well established quantum electromagnetic field theory. Possibility of the experimental verification of the present solution to the easy problem by means of the detection of the evanescent photons in the brain is discussed, and some experimental methods are suggested. As it has been emphasized by Chalmers, any solution to the easy problem cannot be a solution to the hard problem, and the hard problem will require a drastically new approach. This is true even in the physics approach, and certain drastic change of the fundamental framework of theoretical physics may be needed. It is indeed this type of drastic change Penrose wanted to incorporate into the conventional consciousness study by claiming the need of a complete theoretical framework of physics in which both the problems of quantum measurement and quantum gravity can be solved. Unfortunately, quantum gravity sounded like a butcher knife for the shrimp cocktail, and counterarguments have been brought without understanding Penrose's real intention that quantum gravity means the unification of quantum theory with the notion of space-time. He might have a keen insight into the possibility that the unification of quantum theory with space-time structure would solve not only the problem of quantum measurement but also the hard problem in consciousness study. As one of the most interesting approaches from fundamental physics to the hard problem, Nakagomi's idealism theory of physics called quantum monadology will be sketched. In this idealism world model, both of the fundamental theories of modern physics, that is, quantum theory and relativity theory of space-time can be internalized naturally. There, not only the problem of quantum measurement is solved, but also the meanings of space-time, time flow, now, quantum principles of physics, our subjective experience, and so all the physical, biological and social phenomena will be systematized. This talk is based on the joint work with Mari Jibu.


See also:


Pharmacology

02.10-- Abstract No:887

Melatonin and cognition: Was Descartes on to something with the pineal gland?

J.Alexander (Western Oregon University, Department of Psychology, Monmouth Oregon 97361, USA<alexanj@wou.edu>)

Behavioral data from various studies have suggested that the use of Melatonin, a neurohormone secreted by the pineal gland, is effective in treating insomnia and other behavioral conditions. This hormone is considered to be one of the strongest determinants of our most obvious change in conscious states, viz., sleep. In a series of studies designed to assess the psychophysiological effects of Melatonin, the visual and auditory event-related potentials (ERPs) were recorded in 20 subjects (10M, 10F) using a within subjects, single blind, counterbalanced design in which during one session subjects received 3 mg of a placebo and during a second session subjects received 3 mg of Melatonin. ERP data revealed that the P3 component was significantly larger in amplitude for the control (placebo) condition compared to the experimental (Melatonin) condition. Given the assumption that decreases in P3 amplitude indicate lesser engagement of cognitive processes, the results support the notion that the primary hormone related to sleep can be manipulated. Thus, by altering cognitive and conscious states with a substance that is naturally occurring in the body, we may be provided with a paradigm that can be utilized for studies investigating conscious states, resources, and mechanisms. All of this related to a tiny gland that was once considered a primary location for the interaction between body and mind. Indeed, the pineal gland may in an odd way serve such a function.


02.10-- Abstract No:1029

Effects of the novel de antagonists (+) -AJ76 and PNU-9919A on apomorphine-induced disruption of prepulse inhibition

T.B.Virden (Department of Psychology, Western Michigan University, Kalamazoo, MI 49008, USA<x95virden@wmich.edu>) , L.E.Baker, N.F.NicholsK.A.Svensson, , <>

The amplitude of the startle response in humans and rats is decreased when immediately preceeded by a brief, low-intensity lead stimulus. This phenomenon, called prepulse inhibition (PPI) , has been shown to be attenuated in schizophrenic humans and has served as a nonhuman assay to detect the antipsychotic potency of novel compounds. The present study attempted to reverse apomorphine-induced disruption of PPI via the administration of the classical antipsychotic haloperidol, the atypical antipsychotic clozapine, and the novel D3-preferring antagonists, (+) -AJ76 and PNU-99194A. All rats that received vehicle treatement demonstrated significantly disrupted PPI. Haloperidol (0.01-1.0 mg/kg) , clozapine (25 mg/kg) , and (+) -AJ76 (6.75-27 mg/kg) antagonized apomorphine-induced PPI disruption while PNU-99194A yielded no antagonism at any dose tested (1.25-3.0 mg/kg) . These preliminary results imply that teh D2 receptor may play a more major role in PPI than the D3 receptor and that further research is necessary to establish PNU-99194A as a potential antipsychotic compound.


See also:


The binding problem

02.11-- Abstract No:999

Philosophic and neuroscientific aspects of the cognitive binding problem

G.A.Mashour (Georgetown University School of Medicine, 3970 Reservoir Rd, RB-W225, Washington, DC 20007, USA<gmasho01@gumedlib.dml.georgetown.edu>)

A central problem in the neuroscientific account of consciousness is the cognitive binding problem. The problem can be characterized thus: there must be some property of neural activity that unifies the various modalities of perceptual processing in order to create a single, yet complex, conscious event. This question has its modern origins in the Critique of Pure Reason, where Kant posits a "transcendental unity of apperception" as an essential feature of consciousness. Thus, the binding problem has both neuroscientific and philosophic importance. In this paper I examine the current neuroscientific accounts of the binding problem, and demonstrate their inherent theoretical contradictions (I) . I then suggest a new framework for considering the binding problem, and establish conditions for a meaningful solution (II) . Finally, I posit that the Penrose-Hameroff theory of objective reduction satisfies these conditions (III) . The intimate relationship of Kant's philosophy to the cognitive binding problem is elucidated throughout this work.

(I) Many cognitive neuroscientists have posited that simultaneous firing of spatially discrete neuronal subpopulations could account for this phenomenon. I have previously shown how this solution to the binding problem results in theoretical contradictions due to the relativity of simultaneity. I now describe a further contradiction that relates to an implication of 40 Hz theory. It has been suggested by Llinas and Ribary that conscious activity in the brain is not an isotonic map of reality (as first suggested by James) , but is rather a closed system, with sensory information only loosely modulating the brain's intrinsic activity of consciousness. This statement is revealed to be inherently contradictory due to the implicit presupposition of consciousness as an open system. These and other difficulties of the 40 Hz solution to the binding problem are discussed in this section.

(II) Suggested conditions for a meaningful solution to the binding problem are the following:

(a) The contradictions that arise in the above discussion are rooted in the implicit presupposition of consciousness. I believe this presupposition can be revealed concretely in any theory of consciousness. Thus, I posit that any meaningful account of the cognitive binding problem must have the property of consciousness given a priori.

(b) I reject a framework for perceptual processing in which it appears that the brain must carry out a temporal/historical step of binding after it has fragmented sensation into submodality. Binding must be a principle of neural activity, not a problem for it to solve. Kant has made a compelling argument that binding (unity of apperception) is necessary a priori, and not an a posteriori event. Thus, we should not attempt to demonstrate how the brain "solves" the binding problem, but rather establish a framework within which the binding problem ceases to be a problem at all.

(c) Finally, the 40 Hz theory has provided a temporal solution to an essentially spatial problem. Thus, the brain must be show to have spatial, not temporal, properties that obviate the necessity for a binding problem.

(III) The final section of this paper demonstrates how the Penrose-Hameroff theory of objective reduction satisfies the requirements established in section (II) .


See also:


Language

See:


Emotion

02.13-- Abstract No:961

Affective consciousness and the neural origins of the self: The case of animal laughter

J.Panksepp (Department of Psychology, Bowling Green State University, Bowling Green, OH 43403, USA< jpankse@bgnet.bgsu.edu>)

The conceptual framework for our ongoing work on the nature of affective consciousness is based on the potential existence of primal SELF-organizing neural networks in posterior thalamic, deep tectal and underlying periaqueductal regions of the mesencephalon. The interactions of basic emotional circuits and primal representations of the body may provide a primordial body image which is the foundation not only for affective consciousness but higher forms of perceptual and ideational consciousness. The empirical evaluation of such propositions depends heavily on the identification of the neural substrates for basic affective processes, and in this presentation, I will summarize data indicating that other mammals, including lower mammals such as rats, express joy through vocal and related bodily patterns of laughter. This work is premised on the supposition that in humans, laughter and giggling are the best objective indicators of joyful positive affect, since they occur most abundantly during playful social interactions. An understanding of such positive emotions has been hampered by the lack of simple measures of joyful social engagement in "lower" animals. Since the simplest way to induce laughter in children is tickling, we have sought evidence for a comparable phenomenon in young rats by studying their ultrasonic "chirping" during vigorous bodily stimulation. Indeed, such vocalizations (in the 50 KHz range) are common during juvenile play, and we have now discovered that they can also be evoked by rapid manual stimulation (i.e., tickling) . There are differential bodily sensitivities of this response. Stimulation of anterior body areas, which are especially important for arousing playfulness yielded more chirping than stimulation of posterior zones, and full body stimulation yielded the most of all. Analyses of these vocalizations suggest relationships to primate laughter: Tickling is a positive incentive state, as indexed by classical conditioning and instrumental approach tests; it is also correlated to natural playfulness and is inhibited by fearful arousal. These data suggest that a primal form of "laughter" evolved early in mammalian brain evolution, and provide a new way to study the neural sources of positive social-emotional processes (i.e., joyful affect) in other mammals. Since affective feelings may represent one of the earliest forms of consciousness, the understanding of the brain substrates for such responses can help place the study of higher forms of consciousness on a firmer neurological foundation than presently exists. Ongoing studies to analyze the subcortical neural substrates will be discussed. Specific thalamic and mesencephalic areas, and glutamatergic neural systems are presently implicated. We believe these results can be related to new and specific neural conceptions of the primordial SELF, as is more fully discussed in Panksepp (1998, Affective Neuroscience: The Foundations of Human and Animal Emotions, Oxford University Press) .


02.13-- Abstract No:1146

Affect and the 'hard problem': neurodevelopmental and corticolimbic network issues: Implications for ERTAS theories of consciousness

D.F.Watt (Director of Neuropsychology, Quincy Hospital)

Affect (as one of the easy problems?") is largely relegated to the back of the bus as an interesting'coloration' to the 'hard problem' of consciousness, a position that this article attempts to redress. Current theories of consciousness grossly neglect many lines of evidence that emotion is a central organizing process for consciousness. We review four areas that converge on the relationship between consciousness, as a global workspace, and emotion, as a global representation of value: 1) intrinsic relations between three neuropsychological global state functions; 2) putative neural network underpinnings of emotion and their intersections with ERTAS systems; 3) current hypotheses about neural correlates of clinical syndromes that are diseases of consciousness; and 4) current research into neurodevelopmental issues.

From the first vantage point of neuropsychological structure, we examine the interpenetration of three neuropsychological global state functions -- affect, attentional functions and executive functions. Although the distinction between "hard" and easy problems has already been critiqued by Baars and many others, the intrinsic interpenetration of these three global state functions further underlines the specious nature of such distinctions. Conceptual-functional analysis suggests that these global state functions (attentional function, executive function, and affect) are closely tied to the 'hard' problems of self, qualia, and the seamless integration of the more " modular " (or channel) functions that consciousness demonstrates as a fundamental property. All three global state functions should be conceptualized as different dimensions of the principle manifestation of global integrative processes in the brain – namely c-- consciousness itself. Clinical evidence strongly supports this neuropsychological-conceptual analysis, as lesions that generate attentional and executive problems almost universally affect emotional functions also. Typically, lesions of basal ganglia, limbic-paralimbic regions, prefrontal regions, midbrain and diencephalic systems produce admixtures of deficits in these global state functions.

From the second vantage point of neural network underpinnings, affective functions are "supra-modular" functions, involving globally distributed networks running from the base of the brain to the neocortical axis -- the 'limbic system' at this point is so widely distributed that it has very unclear limits. Affect reflects large scale interpenetrations of the 'state space' of 're-entrant' modules in many subcortical and cortical systems. This generates affect's multi-dimensionality and its patterned autonomic, endocrine, motor, subjective pain/pleasure, social/signaling, and cognitive (other/self appraisal) integrations. This composite multidimensional nature of emotion has often generated perspectives on affect analogous to the three blind men inspecting different portions of the elephant. Critical neural network correlates suggesting a close relationship between affect and putative foundations for a global workspace are: 1) the 'limbic' nature of much of the reticular core, particularly its monoaminergic portions; 2) the degree of limbic connectivity to NRT/ILN thalamic systems, particularly the modulation of NRT 'gatelets' by nucleus accumbens, paralimbic cortices, BG, and DM thalamus-prefrontal regions; 3) the reciprocal connections of ILN to reticular core, limbic, BG, and various cortical systems. These limbic connectivities of the non-specific thalamic systems thought to subserve gating and binding functions crucial to consciousness suggest that affect is much more than simple 'coloration, ' and that gating and binding probably depend at least in part on affect's global 'valance tagging' of all other encodings.

From the third vantage point, that of clinical syndromes or "diseases of consciousness, " we examine four 'diseases of consciousness' -- delirium, autism, MPD (DID) , and schizophrenia, with three of these syndromes strongly neurodevelopmental in origin. Schizophrenia, autism, and MPD (DID) demonstrate that early pathology of corticolimbic connectivities or severe affect trauma do not simply generate the expected personality -- affective problems, but produce basic pathology of self/consciousness/qualia. Delirium is also reviewed, as it reflects the collapse of working memory, which has important implications for any theory of consciousness, with disruption of NRT function as a possible final common pathway of its multiple etiologies. In delirium "the lights are on, but no one is home." Confusional states can be generated by focal insults confined to the cingulate, underlining the critical importance of embedded representations of value for attention and the ongoing generation of working memory frames. Without working memory, intact attentional function, or coherent agency, patients with deliriums or confusional states are lacking an organized or lucid consciousness, yet are without stupor/coma. Working memory itself demonstrates a critical embedding of value within implicit goals, suggesting a central and largely neglected principle about consciousness: without representation of value embedded in every working memory frame, there can be no focus, prioritizing, or motivation. This subtle embedding of value in virtually all higher cortical encodings suggests that affect must play a crucial role in any real solution to the "binding problem" – that affective activations tell the brain what is real and what matters.

From the fourth vantage point, neurodevelopmental research literature and the prototype integrative work by Schore serves as an antidote to current assumptions in theories of consciousness that we sprang like Athena from the head of Zeus, and that development of the neural architecture of consciousness is independent from 'good enough' emotional nurturing. We know much less about the neurodevelopment of affect -- the prototypes of attachment behavior, smiling, and separation anxiety in the infant -- than we do about language and vision in the adult. This may be analogous to studying calculus before being able to count on one's fingers. Research suggests that orbitalfrontal and cingulate connectivities are crucial to attachment phenomena and the early matrix of emotional experience with mother, and that the development of the key corticolimbic connectivities that modulate NRT/ILN systems is 'experience-dependent.' Current (very modest) information on early neurodevelopmental processes contributing to development of self suggests a heuristic focus on progressive myelination and synaptogenesis in paralimbic, limbic and basal ganglia regions sitting over the MRF-hypothalamic-brainstem core. The largely unmyelinated status of the NRT-ILN thalamocortical complex during the first two years suggests that in early childhood it cannot serve anything like its central function in the adult, with this ILN-NRT thalamocortical system probably "bootstrapped" via initialization of matrices of representations of value deriving initially from primary attachments. From an evolutionary standpoint, all other systems of higher cortical encoding would need to be "cross-referenced" or "indexed" to a complex matrix of representations of value, as this is the only means for globally integrating multi-modal information processing done by many relatively separate dedicated modular processing systems. Without central representation of value, available "on-line, " and "in real time, " there may be no basis for executive or attentional function at all, consciousness thus being impossible.


02.13-- Abstract No:1196

Symposium: Emotional experience and the frontal lobes

A.W.Kaszniak (Department of Psychology, University of Arizona, 1503 E. University, Tucson, Arizona, 85721<Kaszniak@ccit.arizona.edu>)

Emotion is an integral aspect of human experience, and has been hypothesized to impart significance and value labels to sensory qualia (Ramachandran & Hirstein, 1997) and provide a link between the survival-oriented regulations of the body and consciousness (Damasio, 1994) . Recently, considerable progress has been made in understanding the neurobiology of emotional behavior in animals, but controversy remains (e.g., Damasio, 1994; LeDoux, 1996) concerning the neural correlates and possible functions of conscious emotional experience. This symposium explores current approaches to examining the neural correlates of emotional experience, from the perspectives of neuropsychological, brain imaging, and brain stimulation studies focused upon the frontal lobes. In the first presentation, Alfred Kaszniak and colleagues describe their research involving patients with frontal lobe damage, concluding that mediobasal frontal structures are critical for both emotional experience and autonomic physiologic response. In the second presentation, Richard Lane and colleagues describe their Positron Emission Tomography (PET) research, the results of which are consistent with the hypothesis that supra-callosal and pregenual anterior cingulate cortex participate in primary and reflective conscious awareness of emotion, respectively. Finally, the symposium provides a panel discussion, between the presenters and attendees, focusing upon areas of convergence and divergence in their research, and upon future research possibilities from each of their methodologic perspectives.


02.13-- Abstract No:1197

Conscious experience and autonomic response to emotional stimuli following frontal lobe damage

A.W.Kaszniak (Department of Psychology, University of Arizona, 1503 E. University, Tucson, Arizona, 85721<Kaszniak@ccit.arizona.edu>) , S.L.Reminger, S.Z.RapcsakE.L.Glisky, , <>

In studies employing standardized emotional stimuli (e.g., Greenwald, Cook, & Lang, 1989) , skin conductance response (SCR) magnitude has been found to be directly related to the self-reported conscious experience of emotional arousal. Recently, progress has been made in clarifying the central neuroanatomical substrates of the SCR. Raine, Reynolds, and Sheard (1991) , using magnetic resonance imaging (MRI) , found significant correlations between SCR magnitude and bilateral prefrontal, pons, and left temporal/amygdala area size. Tranel and Damasio (1994) found bilateral ventromedial frontal, bilateral anterior cingulate, and right inferior parietal lesion loci to be consistently associated with defective SCRs to emotional pictures. Damasio (1994) has hypothesized that frontally-damaged patients who do not have an SCR to emotionally- salient stimuli will not have the "conscious body state characteristic of an emotion" (p. 209) , and provided anecdotal examples consistent with this hypothesis. However, there remains a need for systematic studies of frontally-damaged patients, in which SCR and quantitative subjective ratings of emotional experience. Subjects: Ten healthy controls and eight patients with focal frontal lobe damage participated in the study. CT- and/or MRI-confirmed lesion etiologies included head trauma (N=3) , stroke (N=2) , and ruptured ACA aneurysm (N=3) . Materials: The International Affective Picture System (IAPS) slides were employed as the emotionally-arousing stimuli. These slides have extensive normative data available, providing consensus ratings of emotional valence (positive-neutral-negative) and intensity of emotional arousal reported by subjects in response to viewing the slides. For the present study, two valence- and arousal- matched sets of slide images, consisting of 9 pleasant, 9 neutral, and 9 unpleasant slides in each set, were selected.

Procedure: For all subjects, data were collected in two consecutive sessions. Presentation of slide sets A and B was counterbalanced over testing session. Valence and arousal ratings were obtained using Lang, et al. (1980) Self-Assessment Mannequin, which employs a 9-point rating scale. For 5 sec. before slide onset and for 6 sec. during slide viewing, skin conductance was recorded, using standard electrode and amplification procedures The amplitude of the largest SCR with onset falling within the 6 sec. poststimulus interval was recorded.

Results and Discussion: Group comparisons support the hypothesis that frontally-damaged patients show a lack of SCR differentiation in response to neutral vs negatively or positively arousing visual stimuli, and also show a corresponding lack of differentiation in consciously experienced arousal. Examination of lesion location suggests that anterior cingulate damage may be the most critical structure in this regard. Despite abnormal SCR and subjective arousal ratings, these same patients indicate a normal appreciation of the general meaning of emotionally-salient stimuli, as reflected in valence ratings similar to those of controls. This suggests the hypothesis that valence ratings may be more dependent upon the integrity of posterior cerebral regions. Confirmation of this hypothesis will necessitate further research, and require evidence of double dissociation of valence and arousal ratings in patients with frontal vs more posterior lesion location.


02.13-- Abstract No:1198

Subregions within the anterior cingulate cortex may differentially participate in phenomenal and reflective conscious awareness of emotion

R.D.Lane (Department of Psychiatry, University of Arizona College of Medicine, 3301 N. Campbell Ave., Tucson, AZ, 85724<rdlane@CCIT.ARIZONA.EDU>) , E.M.Reiman, G.E.SchwartzG.R.Fink, P.M.L.Chua, R.J.Dolon<>

To examine the neural correlates of selectively attending to subjective emotional responses, we obtained measures of cerebral blood flow in ten healthy men as they viewed emotional picture sets. Twelve picture sets were presented, each consisting of pleasant, unpleasant and neutral pictures from the International Affective Picture System. Pictures were presented for 500 msec every 3.0 seconds. Twelve measures of cerebral blood flow using positron emission tomography and O15-water were obtained in each subject, one for each picture set. During half the scans subjects attended to their emotional experience (indicating on a keypad whether the picture evoked a pleasant, unpleasant or neutral feeling) ; during the other half they attended to spatial location (indicating whether the scene depicted was indoors, outdoors, or indeterminate) . Across subjects, picture sets were counterbalanced across the two attention conditions.

During attention to subjective emotional responses increased neural activity was elicited in rostral anterior cingulate cortex (Brodmann's Area [BA] 32) and medial prefrontal cortex (Z=6.74, p<.001, corrected) , right temporal pole, insula and ventral cingulate (all p<.001, corrected) . Under the same stimulus conditions when subjects attended to spatial aspects of the picture sets activation was observed in parieto-occipital cortex bilaterally (Z=5.71, p<.001, corrected) (1) .

The latter findings are consistent with those of previous studies, which have demonstrated that when attention is directed to a particular feature of a stimulus neural activity is enhanced in structures which participate in the analysis of that stimulus feature. Based on this principle it is reasonable to conclude that rostral anterior cingulate/medial prefrontal cortex participate in the representation of emotional experience.

At the Tucson II meeting we presented data from another study demonstrating that higher scores on the Levels of Emotional Awareness Scale are associated with greater blood flow in a supra- callosal region of the anterior cingulate cortex (BA 24) . This finding is consistent with the view that activity in this region of the anterior cingulate cortex increases as a function of the degree of complexity of, i.e. the amount of information inherent in, emotional experience.

We speculate that these two sets of findings correspond to the distinction between primary and secondary or reflective consciousness. Primary or phenomenal consciousness involves that which a person experiences, while secondary consciousness involves the evaluation, representation and reflection upon the contents of phenomenal experience. Our data are consistent with the hypothesis that supra- callosal and pregenual anterior cingulate cortex participate in primary and secondary conscious awareness of emotion, respectively. The anatomical juxtaposition and interconnection of these two subregions within the anterior cingulate cortex is consistent with the functional inter-relatedness of primary and secondary consciousness. To the extent that these structures also participate in similar functions in non-emotional cognitive tasks, and that the contents of consciousness are limited and are under voluntary control, these findings and conceptual framework could help to explain why such wide variation exists across people in the extent to which emotions and emotional information are incorporated into the contents of consciousness.


02.13-- Abstract No:1199

Changes in normal and pathological emotion associated with transcranial magnetic stimulation (TMS) of the prefrontal cortex

M.S.George (Departments of Psychiatry, Radiology and Neurology, Medical University of South Carolina (MUSC) , 171 Ashley Avenue, Charleston, SC 29425.<georgem@musc.edu>) , Z.Nahas, A.M.SpeerB.D.Greenberg, E.M.Wasserman, R.M.Post<>

Introduction: Transcranial magnetic stimulation (TMS) is a non-invasive method of probing regional brain activity. In TMS, a powerful electrical current is passed through a hand-held electromagnet, generating a focal magnetic field that passes undisturbed into superficial cortex. Single TMS pulses can cause neuronal depolarization due to an induced electrical current in neurons. Repeated trains of TMS (rTMS) can paradoxically activate brain regions, but make them unavailable for participation in neural circuits (producing a temporary functional lesion) . We have been using TMS to explore the role of the prefrontal cortex in mood regulation in health and disease.

Methods / Results: In a series of studies in healthy adults, TMS over the left prefrontal cortex was associated with transient increases in self-rated sadness, with right stimulation having increased happiness. Paradoxically, several studies have shown that in patients with clinical depression, the opposite occurs (e.g. left prefrontal stimulation improving mood, with right no change or worsening) . Conclusions: Although still early in development, TMS appears to be a useful tool for exploring questions of the role of the prefrontal cortex in self-rated (or conscious) emotion.


See also:


Sleep and waking

02.14-- Abstract No:783

Neuropsychology of dreaming consciousness

J.A.Hobson (Laboratory of Neurophysiology, Department of Psychiatry, Harvard Medical School, Boston, MA 02115, USA<hobson@harvarda.harvard.edu>) , D.Kahn, E.Pace-Schott, , <>

Recent evidence from brain imaging and clinical studies of the cortical brain areas involved (and not involved) in rapid eye movement (REM) sleep and dreaming, along with older data on brainstem involvement, allow preliminary identification of neural correlates of dreaming consciousness. For example, clinically, dorsal lateral pre-frontal cortex lesions have been found not to affect normal dreaming (Solms, 1997) , and brain imaging PET studies have found that the pre-frontal cortex regional blood flow activity is negatively correlated with REM and dreaming (Maquet, et al., 1996) . Since wake studies have implicated the pre-frontal cortex with conscious planning, volitional purpose, and logical coherence, its absence in dreaming suggests why dreaming consciousness is devoid of these qualities. Dreaming consciousness is characterized by seeing things that aren't there, believing things that in waking would be dismissed as logically absurd, and mixing up people, places, and times. Moreover, there is no conscious selection of what to dream about. Waking consciousness, on the other hand, very much makes use of the pre-frontal cortex. Hence, the presence or absence of a working pre-frontal cortex is one way in which waking and dreaming consciousness may be neurally distinguished. While the lateral pre-frontal cortex does not seem to be necessary for dreaming, the inferior parietal lobe has clinically been found to be necessary for dreaming (Solms, 1997) , which in waking is correlated with spatial cognition. And brain imaging PET studies have implicated the amygdaloid complex in REM sleep and dreaming (Maquet et al., 1996) . In waking, the amygdala is thought to be necessary for associating affect (especially fear) with sensory input as well as with internal memories. And, in fact, dreaming is episodically emotional, with anxiety being the pre-dominant emotion. Thus, the amygdaloid complex provides for one important aspect of this state of consciousness, namely, its emotional quality. Phenomenologically we would expect to see dreaming consciousness reflect the different neural structures active and not active in dreaming. These data derived from clinical and brain imaging studies allow us to draw tentative conclusions on neural correlates of dreaming consciousness. These brain imaging and clinical data are combined with our own and other investigator's findings of the importance of chemical neuromodulation on differentiating the REM and waking states of consciousness. We combine these divergent areas of investigation to help identify specific chemical neuromodulation and brain structures that differentiate dreaming from waking consciousness.

References

Maquet, P., Peters, J.M., Aerts, J., Delfiore, G., Degueldre, C., Luxen, A., Franck, G. (1996) . Functional neuroanatomy of human rapid-eye-movement sleep and dreaming. Nature vol. 383, pp. 163-166.

Solms, Mark (1997) . The Neuropsychology of Dreams: A Clinico-Anatomical Study. Lawrence Erlbaum Associates, New Jersey.


02.14-- Abstract No:853

The dreaming brain as a self-organizing system

A.Combs (Department of Psychology CPO #1960, University of North Carolina at Asheville, 1 University Heights Asheville, NC 28804-8508, USA<Combs@unca.edu>) , D.Kahn<kahnd@volpe62.dot.gov>, S.Krippner<skrippner@igc.apc.org>, , <>

An argument is made that the dreaming brain can be understood as a self-organizing system, sensitive and particularly vulnerable to a variety of internally generated influences. This sensitivity is due to several changes that occur during the REM stage of sleep. First, the pre-frontal cortex is only minimally activated during REM (Maquet, et al., 1996) and hence the dreaming brain operates with weakened volition, reduced logic and diminished self-reflection. Second, in REM the dreaming brain normally gates out external input and thus operates without the stabilizing influences of external feedback. Further, because the neuromodulatory inhibition mechanism is turned off during REM (Hobson, 1988) , the brain will fire spontaneously at the least provocation. The dreaming brain is also subject to powerful intermittent cholinergic stimulation from brainstem neurons. This cholinergic stimulation is associated with PGO activity.

Cholinergic PGO stimulation activates cortical, sub-cortical, and forebrain areas, inducing bifurcations that impel the brain to self-organize into new stable attractor patterns. Different attractor patterns, corresponding cognitively to distinct episodes within a dream, may be the result of individual PGO bursts. The dream episode (which includes residual memories and amygdala-generated emotions) then is the cognitive correlate of internally generated cortical, sub-cortical, and forebrain neuronal activity, as assemblies of neurons fire in attractor patterns unencumbered by logic circuits and real world feedback. In general, the self-organizing brain is always testing its bifurcation points, but during the waking state when the brain is aminergically inhibited from spontaneously firing and is attentive to real world feedback, stable attractor basins may be long-lived and bifurcations relatively rare. Hence, the waking brain is not normally vulnerable to internally generated input as it is in the REM stage of sleep, which exists, so to speak, on the edge of chaos -- that is, near its bifurcation points.

The present approach is an elaboration of Kahn and Hobson's recent self-organizing theory of dreaming (Kahn & Hobson, 1993) , and similar thinking by Combs and Krippner (in press) . It suggests that previous findings concerning the dynamics and meaning of dreams might, in fact, reflect the inherent self-organizing properties of the brain itself, thus offering a possible meeting ground between the neurosciences and traditional psychological dream research. For example, what psychologists such as Freud and Jung were seeing as narratives and symbols in dreams may, at the same time, have arisen as attractor patterns either already laid down, or newly created by virtue of the self-organizing properties of the exquisitely sensitive dreaming brain.

References

Combs, A., & Krippner, S. (1996) . Dream sleep and waking reality: A dynamical view of two states of consciousness. In: Toward a Science of Consciousness 1996; The second Tucson discussions and debates. Eds. S Hameroff, A Kaszniak, A Scott. MIT Press, Cambridge (in press) .

Kahn, D., & Hobson, J.A. (1993) . Self-organization theory of dreaming. Dreaming, 3, 151-178.

Maquet, P., Peters, J.M., Aerts, J., Delfiore, G., Degueldre, C., Luxen, A., & Franck, G. (1996) . Functional neuroanatomy of human rapid-eye-movement sleep and dreaming. Nature, 383, 163-166.


02.14-- Abstract No:1092

Brain regions preferentially affected during different stages of sleep and wakefulness: A PET study

T.L.Hubbard (Department of Psychology, TCU Box 298920 Texas Christian University, Fort Worth, TX 76129, USA<thubbard@gamma.is.tcu.edu>) , E.M.Reiman, R.R.BootzinD.Bandy, L.S.Yun, T.Muntlinger<>

This exploratory study identified regions of the brain preferentially activated during different stages of sleep and wakefulness. Positron emission tomography (PET) measurements of regional cerebral blood flow (CBF) provided markers of local neuronal activity which, in conjunction with polysomnographic recordings, were used to investigate the neural systems and related mental operations involved in different stages of sleep and wakefulness. A catheter in the left antecubital vein provided bolus injection of 150-water, and PET images were acquired during 60-second scans. The 60-second scan period allowed for the acquisition of multiple images (from waking and from different sleep stages) from each subject, and so subjects served as their own controls. Standard EEG, EOG, and EMG polysomnographic measures verified sleep stage. Twelve right-handed unmedicated adult males free of neurologic, psychiatric, substance abuse, or sleep disorders were studied. Scans were analyzed by the use of a brain mapping algorithm (statistical parametric mapping) which characterized state-dependent changes in regional CBF with increased power. Automated algorithms were used to align sequential PET images in each subject, normalize them for variations in whole brain measurements, transform them into coordinates of a standard brain atlas, generate normalized t-score maps of differences in regional CBF between different stages of sleep and wakefulness, and superimpose these images onto an average of subjects' spatially standardized T1-weighted, volumetric MRIs. Waking was distinguished from Stage 2, Stage 3, and REM sleep by increased CBF in the medial prefrontal, anterior and posterior cingulate, and inferior parietal cortex and by decreased CBF in the occipital cortex. REM sleep was distinguished from Stage 2 and Stage 3 sleep by increases in regional CBF in the thalamus, anterior cingulate cortex, and superior temporal gyrus, and by decreases in regional CBF in the occipital cortex and premotor areas. Stage 3 sleep exhibited significant increases in regional CBF from stage 2 in the vicinity of the occipital cortex and parahippocampal gyri, and significant increases in left hemisphere regional CBF in the hippocampus, superior temporal cortex, and inferior frontal gyrus. Relative decreases in prefrontal cortex, anterior cingulate, and inferior parietal areas during sleep relative to waking is consistent with suggestion that those areas are involved in executive processes and in attention, two types of cognitive processing noticeably decreased during sleep. Greater CBF in cingulate structures during REM relative to Stage 2 and Stage 3 sleep is consistent with previous studies implicating cingulate structures in semantic association, information processing, and emotion. Decreases in CBF in the occipital during REM relative to Stage 2 and Stage 3 sleep may reflect a smaller decrease in CBF in the occipital than in other brain regions. When used as a complement to other research methods, PET can help characterize how the mind and brain participate in different stages of normal sleep and wakefulness, sleep disorders, and other alterations in a person's level of consciousness.


02.14-- Abstract No:1307

Neural ensembles in sleep and waking and the reprocessing of recent experience

B.McNaughton (Department of Psychology, The University of Arizona)

[abstract to follow]


02.14-- Abstract No:1310

EEG correlates of changes of consciousness during the sleep onset period.

T.Murphy (Psychology Department Brock University, St. Catharines, Ontario, L2S 3A1, Canada <rogilvie@spartan.ac.brocku.ca>) R.D.Ogilvie

Intention was manipulated to determine whether sustained conscious attempts to remain awake would alter the process of falling asleep. Eight participants spent 2 non-consecutive nights in the sleep lab during which they were given six, 20 min. nap opportunities - one per hour from 2300 to 0400 hr. On three occasions per night they were asked to fall asleep normally(NS); on three they were asked to remain awake(RA). FFT analyses and visual scoring with Hori's 9-stage system were used to analyze the EEG. Longer sleep latencies and higher incidence of structured mental activity accompanied RA naps. The descent into sleep was characterized by more Hori stage shifts toward higher arousal in the RA condition. Spectral power measures differed between conditions during the 4 min. immediately prior to the first sleep spindle. Intending to remain awake altered the path and slightly delayed, but did not prevent sleep onset.


02.14-- Abstract No:1312

Neurobehavioral functioning during the transitions from wake to sleep and sleep to wake

J.Wyatt (Circadian, Neuroendocrine and Sleep Disorders Section, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115 <jkwyatt@gcrc.bwh.harvard.edu>), R.Bootzin, J.B.J.Allen, J.L.Anthony, M.E.Jewett, D-J.Dijk

Recent studies have confirmed the importance of sleep, the endogenous circadian pacemaker, the sleep onset transition, and sleep inertia in the modulation of waking neurobehavioral functions (e.g., reaction time, short-term memory, cognitive throughput, mood, subjective alertness). Explicit memory for meaningful auditory stimuli presented during the sleep-onset transition is impaired by as little as 10 minutes of subsequent sleep, via a mixed anterograde-retrograde amnesia process. Results from the forced desynchrony protocol, where volunteers are placed on a non-24hr sleep/wake schedule (e.g., 13.33h wake/ 6.67h sleep) in temporal isolation, have found a nonlinear interaction between the sleep/wake homeostat and the circadian pacemaker in the regulation of performance on a computerized neurobehavioral test battery. These results suggest basic neurophysiologic mechanisms of importance in the regulation of consciousness.


See also:


Specific brain areas

See:


Miscellaneous

02.16-- Abstract No:931

PET imaging of systematic cerebral changes after psychological treatment of obsessive-compulsive disorder: A causal role for consciousness in the brain?

J.M.Schwartz (Dept. of Psychiatry, UCLA School of Medicine, 760 Westwood Plaza, Room 67-468, Los Angeles, CA 90024-1759, USA< jmschwar@ucla.edu>)

Obsessive-compulsive disorder (OCD) is a common neuropsychiatric condition characterized by bothersome intrusive thoughts and urges which frequently lead to dysfunctional repetitive behaviors such as excessive hand washing or ritualistic counting and checking. There is well-documented evidence implicating faulty modulation of certain aspects of frontal cortex function by the striatum in the pathophysiology of this condition. Studies utilizing PET have demonstrated systematic alterations in cerebral activity in OCD patients successfully treated with drug-free cognitive- behavioral therapy. Essential features of this treatment involve educating patients to regard the intrusion of OCD symptoms into consciousness as the manifestation of a "false brain message, " and training them to willfully select alternative behavioral responses when experiencing these bothersome thoughts and urges. This process of willful behavioral change is difficult to perform and requires significant pain tolerance. However, it results in significant symptom relief over a period of 10 weeks, accompanied by systematic changes in metabolic activity in fronto-striatal circuits involving the orbital and anterior cingulate cortices. These circuits have been implicated in OCD symptoms by a substantial amount of data collected over the past decade.

Monitoring the internal experiences of OCD patients during treatment provides substantial information about how functional activity in these brain regions is experienced by humans. What stands out as the key predictor of clinical success in cognitive-behavioral treatment is a patient's ability to utilize cognitive insight concerning the true nature of a pathological urge to perform a compulsive behavior (e.g., "That feeling just the result of a false message from my brain") in order to change the meaning and/or value they place upon the internal experience of the symptom (e.g., "I'm not going to let that bothersome urge make me do a compulsive behavior.") When this change in meaning and/or valuation reaches a threshhold consistent with the patient tolerating the discomfort the brain activity causes, while refusing to respond to it in a pathological manner (e.g., repetetive washng and checking) , the metabolic activity in the brain circuitry causing the discomfort changes in ways related to significant clinical improvement.

The philosophical position known as epiphenomenalism views conscious experience as the result, but not the cause, of physical activity in the cerebrum. However, the issue of the role of interpretation in the response to brain activity, specifically the question of what meaning and/or value the human mind places on the internal experience of any particular electro-chemical event in the cerebrum, does not seem to be adequately addressed by this view. This is especially so insofar as it involves the realtionship beween any particular act of understanding and/or valuing a brain signal, the type and quality ot behavior that follows it, and the nature of subsequent brain signals. Brain imaging investigations into the profoundly complex relationships between the understanding/valuation of specific brain signals and subsequent behaviors and brain activities is an area of potentially great importance.


02.16-- Abstract No:951

The limited processing capacity of the brain and mind: implications for understanding consciousness mechanisms?

D.Nikolic (Department of Psychology, The University of Oklahoma, 455 W. Lindsey, Norman, OK 73019, USA<dnikolic@oupsy.psy.ou.edu>)

Recent discoveries of importance of neural synchronized activities have significant implications on understanding how the brain produces its cognitive behavior. Models based on these discoveries rely on dynamical activity through neural synchronization and are replacing the traditional neural networks that mostly rely on static mapping of information. Limited correlational dimensionality of EEG activity suggests limited processing capacity of dynamical activity which might explain limited processing capacity in conscious-voluntary processing. We hypothesize that through learning and skill development the brain changes information processing from dynamical toward traditional mapping decreasing the need for limited resources. The hypothesis is supported by the recent finding that the chaotic dimensionality of motor movements decreases with practice. This hypothesis has several important implications for understanding consciousness: First, the consciousness heavily relies on low dimensional dynamical activity. Second, automatic processes that are under conscious control (i.e., eye blink) should employ processing based on dynamical activity while those that are not under conscious control (i.e. patellar reflex) should rely on mapping only (i.e. only excitation and inhibition) .


02.16-- Abstract No:973

The ghost in the nerve cell: a critique of labelled line theory

D.Rose (Department of Psychology, University of Surrey, Guildford, Surrey GU2 5XH, U.K.<d.rose@surrey.ac.uk>)

How do we become subjectively aware of the quality of a sensory event? One answer, proposed in the early nineteenth century, is that different stimuli activate different neural pathways, which have 'specific nerve energies'. This is nowadays called the theory of 'labelled lines': each sensory message is accompanied by some 'extra quality' that gives a clue to its origin. Yet although the nature of that quality has never been made clear, labelled line theory continues to be used in modern visual psychophysics: labels for stimulus location, spatial frequency, colour, etc. are freely postulated to explain numerous aspects of both behaviour and perception.

The modern usage is confused, however. Firstly, distinctions are not made between a number of possible theories. (i) Level of description: labels are variously assumed to exist at the neuronal level (physical or chemical structures or processes) , the informational level (preconscious or unconscious processing) or at the subjective level (in the conscious aware 'mind') . Yet it is often implicitly assumed a label is simply identical at one level and another, as though for example the existence of a neuronal label explains a subjective quality directly. (ii) Physical location in the brain: e.g. some say the labels are attached to receptor cells, others that labels exist at 'higher' stages. (iii) Ontogeny: how do labels form (innate or learned?) . (iv) How many labels can be carried by each nerve axon? (v) How do labels acquire their meaning (including their quantitative calibration) ?

Secondly, what might be the physical realization of a label? Cognitive representation theory states that codes may be divided into two types: extrinsic (symbols that must be processed or read according to rules) , or intrinsic (built into the system hardware) . For example, at the neuronal level, labels might be: (i) Chemical 'luggage tags' attached to axons. (ii) Neuronal firing patterns (e.g. 40 Hz oscillations) . (iii) Ratios or patterns of activity across a set of neurones. (iv) The cytoarchitectonic location of the nerve cell body. Possibilites i-iv could convey extrinsic codes, and iv intrinsic -- but which code is meant is not specified by researchers who use labelled line theory.

The whole concept itself also has philosophical problems. First, it is circular (How do you know we have labels? From the way we behave and/or perceive. But why do we behave/perceive the way we do? Because we have labels.) . It is also too general (there is no limit on what types of label can be postulated, nor how many) ; it applies to bottom-up sensory processing only (we know there are also recurrent feed-back connections in sensory pathways -- what labels do they carry?) ; and for perception it requires a Cartesian theatre where the labels are read (like the Cartesian soul reads the signs projected onto the pineal body) .

It is concluded that the theory of 'labelled lines' does not provide an explanation for subjective perception. It is also dubious whether it contributes towards an understanding of subconscious information processing.


02.16-- Abstract No:1169

From Aristotle to zoology -- via DNA and developmental neurobiology,

H.G.Kiefer (130 N. Cuyler Avenue, Oak Park, IL 60302, USA)

Genetic concepts are now being integrated into developmental biology, with the recent discoveries of organizer genes such as the Homeobox (Hox) and hedgehog-type arrays in DNA. Such genes have been shown to determine the final 3-dimensional structure of tissues (and more inportantly, the interactions of the structural parts or these tissues to produce the final functioning behavior.) This paper outlines a new concept, the application of genetic organizing gene concepts to the embryological development at the brain and the subsequent structure and functioning of the neuronal arrays in the human brain. A review of the literature of developmental neurobiology and camparative neuroanatomy of the past 15 years suggests that, while subtle, genetically directed patterning in the brain can be reasonably hypothesized, and more excitingly, this genetic patterning links, in a logical way, human brain structures to many key mental functions such as instinctual (i.e. hardwired) and learned (based on softwired) behaviors, along with their associated memory fonmrtion, and to higher human behaviors as the capacity for symbolisation, with its rise into higher consciousness.

Taking a cue from Konrad Lorenz, in his stimulus-releaser chains of inborn behavior in birds, and more recently from Seymour Benzer, a sound genetic underlay is seen for sequential "fragments" of key survival behaviors, such as those for courtship, mating and aggression, which would lend itself to storage in sequential segments of development-directing DNA such as is embodied in the Homeobox concept. In such a system, key multi-modal sensory input patterns, when arriving simuitaneously, (i.e. a "gestalt") would seek out a particular prewired little "microcircuit-like" part of the brain, threshold a key neuron in that part by their simultaneous arrival, hence triggering a preprogrammed configuration of appropriate motor actions (and possibly, hormonal releases) . For an extended grouping of survival behavior "microchips", one would have to envision a stack of these "microchip"-like circuits, each trailing a set of connecting neurons that bring in the multi-modal sensory pattern ("gestalt") and each projecting forth neurons that connect to other centers to activate a preprogrammed complex of motor (and hormonal actions appropriately constituting the survival behavior for that particular incoming pattern of sensory messages. For reasons that will be further developed in this talk, the hippocampus sits at the ideal position structurally, neurobehaviorally, evolutionarily, etc. to perform this function of a collection of fragmented survival behaviors. This paper proposes that the hippocampus contains segmental arrays of both neurons and behavior encodements that act as a homeobox-determined structure, programming not only complex hardwired behavious, but interfacing with the neocortex during its development to direct its neuroembryalogical interconnections and functioning. While in lesser and more ancient animals, all that exists of a cortical structure is the hippocampus, perched like a cap, uppermost and medially, over the primitive brainstem, as evolution proceeded, this structure (containing all the essential hardwired programs of survival response) would accumulate new succeseful strategies, giving each higher organism an increased number of survival strategies, eaeh of which could be triggered by increasingly more finely shaded inputs, lending greater depth, subtlety, and potentially conscious choice between parts of this storehouse of survival strategies. Ar the hippocampus sweeps down and back in advancing evolution, it forces all the 6 new layers of the neocortex to migrate throuch it as they form, leaving wiring set up between its trailing connections (now the new arferents) of the cingulate gyrus, and all parts of the specialized new neocortex. Hence, orderly cingulate neuronal connections between correct parts of the now-specialized neocortex and the ancient multi-modal hippocampos, are laid down as the neocortex first is forming. Greatly expanded multimodal sensory input is even possible using this format. Hippocampal "programming" cells, containing appropriate behavior configurations for each patterned connection of incoming sensory stimuli output, via the fornix, back to the thalamus (and hypothalamic areas) forming a loop. The sweeping movement downward and backward of the set of orderly "microchip" stacked behaviors comprising the hippocampus makes room within the limited skull for another greater loop to form -- that of the thalamus and Its expanded servant, the neocortex. Hence a two-loop system is set up reminiscient of recent proposals by Pribram and Harth. Material will be developed in the presentation that links the predictions of this model to Karl Jung's archetypes, Aristotle and MacLean's triune brain proposals, Schopenhauer's advance of the Kantian philosophical revolution, with his concept of "Der Wille", and Pribram's "holographic brain".


02.16-- Abstract No:1231

Concept of conscious representations in light of multiunit recordings

A.Samsonovich (Arizona Research Labs Div. Neural Systems Memory & Aging The University of Arizona, Life Sciences North #384 Tucson, AZ 85724-5115, USA<alexei@nsma.arizona.edu>)

The brain can be viewed as a modeling device that performs simulations of an Internal Cognitive Model of the world (ICM) . This ICM contains the element 'I' that has no counterpart in the real world, but its correlates represent the main interest. It is imposed by the ICM that 'I' is localized in space and is continuous in time, is unique and self-consistent, is aware of all sensory stimuli, is in control of the subject's actions, is free in decision making, etc. These are the error fundamentalis of the ICM that constrain brain dynamics. For instance, 'I' exists only via its representations based on separate brain modules that are specialized and in many cases have no physical ability to exchange their contents. It is likely therefore that in order to maintain mutual consistency as required by ICM, the modules under normal conditions communicate with each other using a "brief code", called a "cartoon" by Nadel and O'Keefe, rather than the actual content of the represented information. This concept of limited communication between modules provides the basis for an explanation of hemineglect and anosognosia. E.g., an impaired module may not be able to process its part of the sensory input, while still being able to discourage other modules from doing its job, using a "brief code" message. Another, not least important function of, probably, the same "brief code" is indexing episodic memory in order to make it available for explicit retrieval or for interleaving. Experimental data suggest that the indexing code is based on an abstract model of space and simply represents location of 'I' in this space (O'Keefe, Nadel, McNaughton, Rolls) . In other words, despite the fact that consciousness is based on distributed representations in the brain, the represented thing itself ('I', as opposed to the body image and to the attention focus) appears to be localized in spatial and other dimensions, and its location is the context used for binding as well as for long term memory indexing. Is the localized shape of the 'I'-representation structureles? No: it may consist of several items connected by spatial, logical, causal or functional relations that are separated by phases of the theta rhythm in the hippocampus (the whole representation oscillates) . It is likely that in the neocortex as well conscious representations involve phase-locked oscillations (Lisman) . Accordingly, there are indications that phase-locked high-frequency oscillations in the visual system, that are presumably responsible for feature binding, correlate with conscious perception. Thus, assume two kinds of representations involved in conscious sensory perception: 1) without oscillatory structure, not representing 'I', "unconscious"; and 2) with oscillatory structure, representing 'I', "conscious". It follows from the above that "conscious" representations must originate at the destinations of sensory streams such as prefrontal cortex and dentate gyrus, and propagate backwards, parallel to the same pathways, toward sensory inputs, undergoing refinement and becoming more specific during this back-propagation. This conclusion about back- propagation of the coherent oscillatory structure in sensory systems seems to be recently confirmed experimentally (W. Singer, private communication) .


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