PARIS, May 04, 2010 (BUSINESS WIRE) -- The 18th Colloque Medecine et Recherche of the Fondation Ipsen dedicated to the Neurosciences series held on 3 May 2010 was entitled "Characterizing Consciousness: From Cognition to the Clinic ?" Fifteen of the foremost scientists in this field presented testable theoretical models of consciousness and discussed how our understanding of the role that consciousness plays in our cognitive processes is being refined -- with some surprising results. At last being able to look into the human mind at work is both very exciting and somewhat daunting. As well as providing a window into the current state of this field, the meeting was likely to stimulate a lively debate about some of the issues and implications raised by this work. The meeting has been organised by Stansilas Dehaene (Unite INSERM-CEA de Neuro-Imagerie Cognitive, Gif sur Yvette, France) and Yves Christen (Fondation Ipsen, Paris, France).
We all know subjectively that we are conscious but what is consciousness? What function does it serve in our lives and the success of the human species? These knotty problems have long been considered as too slippery for scientific analysis and so have been mainly the concern of philosophers. The advent of sophisticated brain imaging technologies and high-powered computer analysis in the past 25 years has finally allowed experimental access to the neural correlates of the conscious state, as well as to the residual consciousness of brain-damaged patients.
We experience consciousness as an awareness of ourselves, the environment around us and how we respond to it. The only way we can know that other people also have this awareness is through their responses to our questions, which requires communication (Adrian Owen, University of Cambridge, Cambridge, UK). Because this highly subjective process was until recently the only available tool, examining the workings of consciousness was considered to be a topic not amenable to scientific investigation. The development of brain imaging using functional magnetic resonance imaging and of multi-electrode arrays for recording electrical brain potentials, combined with computerised signal analysis, has at last provided objective methods for correlating brain activity with subjective reporting and with precisely defined psychological testing. This technology is providing data about the evolution of consciousness and the neural circuits that seem to mediate awareness; it is allowing the testing of theoretical models of consciousness; and it is providing insights into how much of what we consider to be conscious processing actually lies outside our awareness and ways to assess the awareness of brain-damaged patients.
Language is one essential part of conscious experience but how it evolved is still hotly debated. An alternative to the Chomsky proposal that it emerged fully formed in early humans was explored: that language evolved gradually in a process linked to the development of bipedalism, which had the consequence that infants are born in a dependent state and require months of face-to-face interaction with the mother (Herbert S Terrace, Columbia University, New York, USA). This would have allowed mother and child to share attention, providing a basis for naming events and objects. Another antecedent to consciousness seems likely to have been the decision-making processes that all animals make when selecting which action to perform. By selecting brain circuits instead of selecting action, humans may have generalized from 'deciding to do' to 'deciding to consider', leading to deliberation and reasoning (Michael N Shadlen, University of Washington, Seattle, USA).
The boundaries of conscious awareness may not lie quite where we assume they do. Subconscious processes still play a large part in decision making: brain imaging during tests involving choice allows the experimenter to predict the choice before the subject is aware of it (John-Dylan Haynes, Charite-Universitatsmedizin, Berlin, Germany). The prediction is accurate even in real-life situations, such as deciding which car to buy. Sub-conscious motivation can also be powerful -- larger subconscious incentives produce greater physical effort -- and associations between subliminal clues and gambles can be learned (Mathias Pessiglione, Inserm U610, CHU Pitie Salpetriere, Paris, France). Dopamine neurotransmission in the basal ganglia seems to be important for this subliminal processing. Electrical stimulation studies show that even some aspects of generating movements appear to be outside conscious awareness (Angela Sirigu, Institut des Sciences Cognitives, Bron, France).
Two related theories of consciousness were discussed: the neural self (Antonio Damasio, Brain and Creativity Institute, University of Southern California, Los Angeles, USAF) and the global neuronal workspace (GNW; Jean-Pierre Changeux, College de France et Institut Pasteur, Paris, France; Dehaene), and experimental tests of them has been presented. The neural self envisages a multi-level process that describes the emergence of subjectivity from interoceptive signals and primordial feeling states. The GNW hypothesis was proposed in 1998 to establish causal links between neural and behavioural and mental levels. Well-defined behavioural tasks that are experimentally accessible have been used to test it.
The neuroanatomical bases of both these concepts have been identified (Damasio; Changeux) and predictions of the GNW are being tested using electrophysiological recording during subliminal and conscious processing of visual stimuli (Dehaene). One question is how do different areas of the cortex and subcortical structures identify what features in the ongoing barrage of stimulation are associated. During subliminal visual stimulation, local activation does not propagate to more distant areas, even in the gamma-band activity of the electro-encephalogram, which is thought to promote long-range integration (Dehaene). The more global role of synchronised gamma-band activity is demonstrated in selective attention experiments in monkeys, where it influences the coding of stimulus orientation (Fries, Radboud University Nijmegen, Nijmegen, The Netherlands). Rather surprisingly, individuals have their own characteristic patterns of gamma-band synchronisation, which seems from twin studies to be genetically determined. Slow cortical potentials are also thought to be an indicator of conscious processing (Marcus Raichle, Washington University School of Medicine, Saint Louis, USA).
A glimpse into imaginative thinking and conscious precepts as they are formed is being afforded by electrical recordings during surgery from the brain structures involved in emotion, memory and attention (Moran Cerf, California Institute of Technology, University of California, Los Angeles, USA). Thoughts that have identifiable brain responses are displayed visually on a screen in front of the patient, revealing a competition between the internal process and the external stimulus.
The clinical diagnosis and management of brain-damaged patients is benefiting from the new technologies as well as from the identification of brain areas, cortical and subcortical, involved in conscious and subconscious processing, which many of the speakers reported on. These patients may be left in a vegetative state, showing no signs of awareness or voluntary movement, or minimally conscious, when they are unable to communicate and a crucial question has long been whether in these states they are actually conscious without displaying external signs of awareness. Based on the GNW theory, a set of auditory tests combined with electrical recording has been devised that helps to distinguish brain activity in conscious and non-conscious states (Lionel Naccache, Institut du Cerveau et de la Moelle epiniere, CHU Pitie Salpetriere, Paris, France). Neuroimaging and brain-computer interfaces are enabling clinicians to differentiate more precisely between involuntary and voluntary movements, revealing that up to half the patients diagnosed as in a vegetative state have signs of conscious responses, and that they are not 'neo-cortically dead' but have disconnected islands of cortical activity (Steven Laureys, Universite de Liege, Liege, Belgique). However the use of functional magnetic resonance imaging to infer awareness has its limitations (Owen).
The Fondation Ipsen
Established in 1983 under the aegis of the Fondation de France, the mission of the Fondation Ipsen is to contribute to the development and dissemination of scientific knowledge. The long-standing action of the Fondation Ipsen aims at fostering the interaction between researchers and clinical practitioners, which is indispensable due to the extreme specialisation of these professions. The ambition of the Fondation Ipsen is to initiate a reflection about the major scientific issues of the forthcoming years. It has developed an important international network of scientific experts who meet regularly at meetings known as Colloques Medecine et Recherche, dedicated to six main themes: Alzheimer's disease, neurosciences, longevity, endocrinology, the vascular system and cancer science. Moreover, in 2007, the Fondation Ipsen started three new series of meetings. The first series is an annual meeting organized in partnership with the Salk Institute and Nature and focuses on Biological Complexity; the second series is the "Emergence and Convergence" series with Nature, and the third with Cell and the Massachusetts General Hospital entitled "Exciting Biologies". Since its beginning, the Fondation Ipsen has organised more than 100 international conferences, published 70 volumes with renowned publishers and 210 issues of a widely distributed bimonthly newsletter Alzheimer Actualites. It has also awarded more than 100 prizes and grants.
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