02.00-- Abstract No:1323
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
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
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
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
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
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
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
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
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
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.
02.02-- Abstract No:789
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
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
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
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
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
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
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
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.
02.03-- Abstract No:750
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
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
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.
02.04-- Abstract No:925
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).
02.05-- Abstract No:1114
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
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.
02.06-- Abstract No:873
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
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
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
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
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
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
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
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
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
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.
02.08-- Abstract No:1220
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.
02.09-- Abstract No:933
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 (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
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
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.
02.10-- Abstract No:887
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