Monday July 15 16:30-18:30
Ethical implications of detecting covert awareness in disorders of consciousness
Chairs: Adrian M. Owen (Cognitive Neuroscience and Imaging, Western University, Ontario, CA),
Andrew Peterson (Rotman Institute of Philosophy, Western University, Ontario, CA)
Recent findings in cognitive neuroscience (Monti et al .2010, Owen et al.2006) suggest that functional mag- netic resonance imaging (fMRI) may be a viable means for detecting covert awareness in the vegetative state (VS). This research opens a promising new avenue for developing brain-computer interfaces (Naci et al. 2012) that compliment the current diagnostic criteria of disorders of consciousness (DOC), thereby increasing the effectiveness of diagnostic screening in this patient group. Given the high rate of misdiagno- sis in this population (Andrews et al. 1996, Childs et al. 1993), actively seeking out patients, who retain conscious awareness despite a clinical diagnosis of VS, is of the highest importance. Moreover, this tech- nique may also permit patients, who are consciously aware and have high levels of preserved cognition, to meaningfully engage in the decision making process related to their own medical care. To date, one patient, previously diagnosed as vegetative for approximately five years, was able to successfully answer a series of autobiographical ‘yes’ or ‘no’ questions correctly overrepeated fMRI scanning sessions (Montietal.2010).
A natural step forward in this research program, therefore, is to apply similar neuroimaging methods to address medical questions relevant to individual DOC patients (Peterson et al. in preparation). Though these scientific findings appear highly promising in principle, incorporating any neuroimaging--based method into clinical setting will require satisfaction of established ethical and legal norms of medical practice. In particular, these concerns include: determining how information acquired from such techniques will be disclosed to patients’ families, what the cost of running such tests will be, whether any individual DOC patient is capable of making medically relevant decisions with these techniques, and what type of ques- tions we ought to be asking this patient population. We propose a symposium that brings together three different perspectives on this problem: neuroscience, neurology, and clinical ethics.
The first perspective, offered by Drs. Lorina Naci PhD and Daniel Bor PhD, both neuroscientists working with these neuroimaging paradigms, will shed light on practical obstacles and ways forward focusing neuroimaging to assess residual cognition in DOC patients.
The second perspective, offered by Dr. Bryan Young MD, a clinical neurologist working directly with this patient group, will highlight the difficulties as well as the potential that neuroim- aging holds for DOC patients in the medical setting.
Finally, Dr. Charles Weijer MD, PhD and Andrew Peterson MA, both medical ethicists and philosophers of science, will offer views on the overarching ethical standards relevant to this research. Dr. Adrian M. Owen, a neuroscientist working in this field, will chair the session.
We hope that this interdisciplinary approach will facilitate a novel and productive conversation about the merits of this research and future directions for using it in the clinical setting.
Using fMRI to assess conscious awareness in patients with disorders of consciousness– practical considerations
Lorina Naci (Experimental Psychology, Western University, Ontario, CA)
Using multiple neuroimaging techniques to assess the quality of conscious awareness in DOC patients
Daniel Bor (Cognitive Neuroscience, Sackler Centre for Consciousness Science, University of Sussex, Brighton, U.K.)
Obstacles at the interface between advances in cognitive neuroscience and clinical practice
Bryan Young (Neurology and Critical Care Medicine, Western University, Ontario, CA)
Conceptual foundations for assessing decision-making capacity in disorders of consciousness
Andrew Peterson (Rotman Institute of Philosophy, Western University, Ontario, CA)
Navigating the transition between research and treatment when integrating novel neuroimaging techniques in medical practice
Charles Weijer (Bioethics, Rotman Institute of Philosophy, Western University, Ontario, CA)
Showing posts with label Symposium. Show all posts
Showing posts with label Symposium. Show all posts
Monday, July 15, 2013
Symposium 3: Beyond the contrastive method
Monday July 15 09:30-11:30
Beyond the contrastive method: How to separate the neural correlates of consciousness from its precursors and consequences
Chair: Lucia Melloni (Dep’t of Neurophysiology, MPI Frankfurt, DE/Columbia University)
The most prevalent approach to study the neural correlates of consciousness (NCC) today is to contrast conditions in which conscious perception occurs with conditions in which it does not. Here, conscious- ness is treated as the dependent variable and then correlated with brain activity. This “contrastive method” has brought about important insights into the NCC. However, despite this apparently straight- forward approach, results are inconclusive and contradictory (e.g., it is still debated whether the NCC occurs early or late, or whether it is expressed in local or distributed brain activity). This discord can be understood when considering a methodological pitfall in the contrastive method: The contrast between conscious perception and unconscious processing confounds the NCC with processes that necessarily precede and follow conscious perception (pre-NCC and post-NCC, respectively) without directly contrib- uting to subjective experience.
It is not straightforward to arbitrate which previous results address the NCC-proper and which reflect other processes. In this symposium we will outline the shortcomings of the contrastive analysis, put forward a new taxonomy that differentiates the processes besetting the NCC- proper, and propose novel experimental approaches to dissociate the NCC-proper from its antecedents and consequences. We review M-EEG and ECOG studies that have employed these new approaches to probe which neural process directly correspond to the NCC. This evidence suggests that previous results may have indeed missed the NCC and reported pre-NCC/post-NCCs. Finally, we will discuss how this new taxonomy relates to prevalent theories of consciousness, arguing that some theories might be about post-NCCs instead of NCC.
Distilling the Neural Correlates of Consciousness
Lucia Melloni (Dep’t of Neurophysiology, MPI Frankfurt/Columbia University)
Using MEG to track conscious access and its non-conscious consequences
Stanislas Dehaene, Lucie Charles (Inserm-CEA Cognitive Neuroimaging Unit, Paris, FR)
Isolating NCCs that are necessary and sufficient for visual awareness
Michael Pitts (Dep’t of Psychology, Reed College)
Core vs. Total NCC
Ned Block (Dep’t of Philosophy, New York University)
Beyond the contrastive method: How to separate the neural correlates of consciousness from its precursors and consequences
Chair: Lucia Melloni (Dep’t of Neurophysiology, MPI Frankfurt, DE/Columbia University)
The most prevalent approach to study the neural correlates of consciousness (NCC) today is to contrast conditions in which conscious perception occurs with conditions in which it does not. Here, conscious- ness is treated as the dependent variable and then correlated with brain activity. This “contrastive method” has brought about important insights into the NCC. However, despite this apparently straight- forward approach, results are inconclusive and contradictory (e.g., it is still debated whether the NCC occurs early or late, or whether it is expressed in local or distributed brain activity). This discord can be understood when considering a methodological pitfall in the contrastive method: The contrast between conscious perception and unconscious processing confounds the NCC with processes that necessarily precede and follow conscious perception (pre-NCC and post-NCC, respectively) without directly contrib- uting to subjective experience.
It is not straightforward to arbitrate which previous results address the NCC-proper and which reflect other processes. In this symposium we will outline the shortcomings of the contrastive analysis, put forward a new taxonomy that differentiates the processes besetting the NCC- proper, and propose novel experimental approaches to dissociate the NCC-proper from its antecedents and consequences. We review M-EEG and ECOG studies that have employed these new approaches to probe which neural process directly correspond to the NCC. This evidence suggests that previous results may have indeed missed the NCC and reported pre-NCC/post-NCCs. Finally, we will discuss how this new taxonomy relates to prevalent theories of consciousness, arguing that some theories might be about post-NCCs instead of NCC.
Distilling the Neural Correlates of Consciousness
Lucia Melloni (Dep’t of Neurophysiology, MPI Frankfurt/Columbia University)
Using MEG to track conscious access and its non-conscious consequences
Stanislas Dehaene, Lucie Charles (Inserm-CEA Cognitive Neuroimaging Unit, Paris, FR)
Isolating NCCs that are necessary and sufficient for visual awareness
Michael Pitts (Dep’t of Psychology, Reed College)
Core vs. Total NCC
Ned Block (Dep’t of Philosophy, New York University)
Sunday, July 14, 2013
Symposium 2: Projecting bodily consciousness
Sunday July 14 10:30-12:30
Projecting bodily consciousness: How the body affects consciousness in personal, peripersonal and interpersonal space
Chairs: Olaf Blanke (Cognitive Neuroscience, Ecole Polytechnique, Lausanne, CH),
Thomas Metzinger (Dep’t of Philosophy, Universität Mainz, DE)
Philosophy of mind, cognitive neuroscience, and neurology stress the importance of bodily input in forming of the experience of self and person. Such bodily aspects of self-consciousness have been shown to arise from the complex integration of interoceptive and exteroceptive body-related signals. An intrigu- ing aspect of bodily self consciousness is that it is not limited to the body itself, but also depends on stimuli related to external objects and in turn influences the experience of the external world. In this sense, bodily self-consciousness extends beyond the limits of our body over the space around us (i.e. peripersonal space) and impacts the interaction with other humans.
The presentations of this symposium will highlight complementary findings from multisensory, motor, and affective approaches and discuss their relavance for self-consciousness. Roy Salomon will focus on how bodily information, that has been shown to alter self-consciousness, can also modulate visual consciousness.
Andrea Serino will show how the boundaries of peripersonal space adapt when interacting with objects and others. Federique de Vignemont will extend the notion of embodiment to the study of social interactions and intersubjectivity.
Body-building-awareness: Bodily factors shaping our consciousness
Roy Salomon (Cognitive Neuroscience, Ecole Polytechnique, Lausanne, CH)
Spatial boundaries of Body-self Consciousness
Andrea Serino (Cognitive Neuroscience, U. Bologna, IT )
Seeing other people’s bodies
Frédérique de Vignemont (Dep’t of Philosophy, Institut Jean Nicod/CNRS, Paris, FR)
Projecting bodily consciousness: How the body affects consciousness in personal, peripersonal and interpersonal space
Chairs: Olaf Blanke (Cognitive Neuroscience, Ecole Polytechnique, Lausanne, CH),
Thomas Metzinger (Dep’t of Philosophy, Universität Mainz, DE)
Philosophy of mind, cognitive neuroscience, and neurology stress the importance of bodily input in forming of the experience of self and person. Such bodily aspects of self-consciousness have been shown to arise from the complex integration of interoceptive and exteroceptive body-related signals. An intrigu- ing aspect of bodily self consciousness is that it is not limited to the body itself, but also depends on stimuli related to external objects and in turn influences the experience of the external world. In this sense, bodily self-consciousness extends beyond the limits of our body over the space around us (i.e. peripersonal space) and impacts the interaction with other humans.
The presentations of this symposium will highlight complementary findings from multisensory, motor, and affective approaches and discuss their relavance for self-consciousness. Roy Salomon will focus on how bodily information, that has been shown to alter self-consciousness, can also modulate visual consciousness.
Andrea Serino will show how the boundaries of peripersonal space adapt when interacting with objects and others. Federique de Vignemont will extend the notion of embodiment to the study of social interactions and intersubjectivity.
Body-building-awareness: Bodily factors shaping our consciousness
Roy Salomon (Cognitive Neuroscience, Ecole Polytechnique, Lausanne, CH)
Spatial boundaries of Body-self Consciousness
Andrea Serino (Cognitive Neuroscience, U. Bologna, IT )
Seeing other people’s bodies
Frédérique de Vignemont (Dep’t of Philosophy, Institut Jean Nicod/CNRS, Paris, FR)
Saturday, July 13, 2013
Symposium 1: Prefrontal cortex
Saturday July 13 10:30-12:30
The role of prefrontal cortex in conscious experience
Chair: Richard Brown (Dep’t of Philosophy, CUNY)
One major divide in consciousness theory is that between higher-order and first-order theories. Inter- preted anatomically, first-order theories of consciousness maintain that consciousness will depend on the activity in the sensory cortices alone while higher-order theories deny that and maintain that consciousness will be reflected, at least in part, in activity of higher-order areas of the brain, most likely frontal-parietal regions.
Virtually all theories of consciousness have a stake in this debate. For instance, besides higher-order thought, and self representational views, Global Workspace Theory, and Information Integration Theory can be seen as versions of higher-order theory in that they posit a role for prefrontal areas in conscious perception, at least in some cases. Also in addition to first-order representation views, recurrent feedback, and attention-based theories can all be seen as versions of the first-order view.
This symposium will bring together two neuroscientists and two philosophers to present the empirical and philosophical case for and against the involvement of the prefrontal cortex in conscious experience.
Local neuronal “ignitions” and perceptual awareness
Rafi Malach (Dep’t of Neurobiology, Weizmann Institute of Science, Tel Aviv, IL)
There are no unconscious phenomenal states
Joseph Levine (Dep’t of Philosophy, U. Massachusetts, Amherst)
Higher order attentional contributions to subjective perception
Dobromir Rahnev (Dep’t of Philosophy, U. California, Berkeley)
Consciousness without first-order representations
Richard Brown (Dep’t of Philosophy, CUNY)
The role of prefrontal cortex in conscious experience
Chair: Richard Brown (Dep’t of Philosophy, CUNY)
One major divide in consciousness theory is that between higher-order and first-order theories. Inter- preted anatomically, first-order theories of consciousness maintain that consciousness will depend on the activity in the sensory cortices alone while higher-order theories deny that and maintain that consciousness will be reflected, at least in part, in activity of higher-order areas of the brain, most likely frontal-parietal regions.
Virtually all theories of consciousness have a stake in this debate. For instance, besides higher-order thought, and self representational views, Global Workspace Theory, and Information Integration Theory can be seen as versions of higher-order theory in that they posit a role for prefrontal areas in conscious perception, at least in some cases. Also in addition to first-order representation views, recurrent feedback, and attention-based theories can all be seen as versions of the first-order view.
This symposium will bring together two neuroscientists and two philosophers to present the empirical and philosophical case for and against the involvement of the prefrontal cortex in conscious experience.
Local neuronal “ignitions” and perceptual awareness
Rafi Malach (Dep’t of Neurobiology, Weizmann Institute of Science, Tel Aviv, IL)
There are no unconscious phenomenal states
Joseph Levine (Dep’t of Philosophy, U. Massachusetts, Amherst)
Higher order attentional contributions to subjective perception
Dobromir Rahnev (Dep’t of Philosophy, U. California, Berkeley)
Consciousness without first-order representations
Richard Brown (Dep’t of Philosophy, CUNY)
Friday, July 6, 2012
Symposium 4 Talk 3: Bottini
Friday, July 6 2012 14:00-16:00 @ Dome Theatre
Symposium 4: "Balancing the Self: Vestibular Contributions to Self-Consciousness"
Talk 3: "Is there a vestibular-somatosensory interaction? Evidence from brain-damaged patients and healthy participants"
Gabriella Bottini (Psychology Department, University of Pavia, Italy)
SUMMARY
Signals from the vestibular system make a crucial contribution to everyday behaviours. No primary vestibular cortex has been identified, rather several multimodal areas integrate vestibular, visual and somatosensory signals. Functional imaging results revealed a clear anatomical overlap of vestibular and somatosensory projections in a number of parietal areas. Moreover, clinical evidence suggests a direct functional link between these sensory systems: a temporary remission of tactile imperception has been observed after left cold caloric vestibular stimulation in right and left brain-damaged patients. Further, psychophysical studies showed that vestibular stimulation improves detection of touch but, intriguingly, it also dramatically increases the threshold for detecting pain. These results lead to the suggestion that specific cross-modal perceptual interactions occur between vestibular and somatosensory systems. Successful interaction with the environment involves constant adjustment and updating of multisensory inputs. The vestibular system seems to play a crucial role in influencing processing within other individual sensory channels.
Symposium 4: "Balancing the Self: Vestibular Contributions to Self-Consciousness"
Talk 3: "Is there a vestibular-somatosensory interaction? Evidence from brain-damaged patients and healthy participants"
Gabriella Bottini (Psychology Department, University of Pavia, Italy)
SUMMARY
Signals from the vestibular system make a crucial contribution to everyday behaviours. No primary vestibular cortex has been identified, rather several multimodal areas integrate vestibular, visual and somatosensory signals. Functional imaging results revealed a clear anatomical overlap of vestibular and somatosensory projections in a number of parietal areas. Moreover, clinical evidence suggests a direct functional link between these sensory systems: a temporary remission of tactile imperception has been observed after left cold caloric vestibular stimulation in right and left brain-damaged patients. Further, psychophysical studies showed that vestibular stimulation improves detection of touch but, intriguingly, it also dramatically increases the threshold for detecting pain. These results lead to the suggestion that specific cross-modal perceptual interactions occur between vestibular and somatosensory systems. Successful interaction with the environment involves constant adjustment and updating of multisensory inputs. The vestibular system seems to play a crucial role in influencing processing within other individual sensory channels.
Symposium 4 Talk 2: Lopez
Friday, July 6 2012 14:00-16:00 @ Dome Theatre
Symposium 4: "Balancing the Self: Vestibular Contributions to Self-Consciousness"
Talk 2: "Vestibular and multisensory foundations of self-location and self-other distinction"
Christophe Lopez (Laboratoire de Neurosciences Intégratives et Adaptatives Centre National de la Recherche Scientifique, Université de Provence, France)
SUMMARY
The vestibular system provides concurrent signals about gravity and one’s body position and motion in space. I will argue that vestibular signals play a crucial role in unifying bodily and extracorporeal signals necessary for self-location and self-other distinction. The core vestibular cortex overlaps with the temporo-parietal region, insula and intraparietal sulcus, three brain regions involved in self-processing. First, I will show that artificial stimulation of the vestibular system (caloric and galvanic vestibular stimulation) can interfere with these brain regions and modulate self-location and the conscious experience of the body (mental representation of the body shape and size, body ownership). Finally, I will present psychophysical data showing that, by distinguishing self-motion from other- and environment-motion, vestibular signals contribute to the subjective experience of being a self.
Symposium 4: "Balancing the Self: Vestibular Contributions to Self-Consciousness"
Talk 2: "Vestibular and multisensory foundations of self-location and self-other distinction"
Christophe Lopez (Laboratoire de Neurosciences Intégratives et Adaptatives Centre National de la Recherche Scientifique, Université de Provence, France)
SUMMARY
The vestibular system provides concurrent signals about gravity and one’s body position and motion in space. I will argue that vestibular signals play a crucial role in unifying bodily and extracorporeal signals necessary for self-location and self-other distinction. The core vestibular cortex overlaps with the temporo-parietal region, insula and intraparietal sulcus, three brain regions involved in self-processing. First, I will show that artificial stimulation of the vestibular system (caloric and galvanic vestibular stimulation) can interfere with these brain regions and modulate self-location and the conscious experience of the body (mental representation of the body shape and size, body ownership). Finally, I will present psychophysical data showing that, by distinguishing self-motion from other- and environment-motion, vestibular signals contribute to the subjective experience of being a self.
Symposium 4 Talk 1: Lenggenhager
Friday, July 6 2012 14:00-16:00 @ Dome Theatre
Symposium 4: "Balancing the Self: Vestibular Contributions to Self-Consciousness"
Talk 1: "Vestibular contribution to multisensory mechanisms underlying the sense of self"
Bigna Lenggenhager (Social and Cognitive Neuroscience Laboratory, Psychology Department, Sapienza University, Italy)
SUMMARY
Data in neurological patients with disturbances in the bodily self suggest an important role of vestibular processes in global aspects of the self such as self-location and first-person perspective. We used mental imagery and multisensory bodily illusions to simulate aspects of such neurological conditions in healthy participants to investigate underlying functional and neural mechanisms. In these experiments both vestibular stimulation as well as visuo-vestibular conflicts interfered with global aspects of the self, confirming a contribution of vestibular processing to a stable sense of self, localized at a specific position in space with a single perspective on the world. Functional magnetic resonance imaging revealed that temporo-parietal junction (TPJ) activity reflected experimental changes in self-location and first-person perspective due to multisensory conflicts. This finding relates again to data in neurological patients that suggest integration of vestibular, somatosensory and visual signals in the TPJ are crucial for a stable sense of self.
Symposium 4: "Balancing the Self: Vestibular Contributions to Self-Consciousness"
Talk 1: "Vestibular contribution to multisensory mechanisms underlying the sense of self"
Bigna Lenggenhager (Social and Cognitive Neuroscience Laboratory, Psychology Department, Sapienza University, Italy)
SUMMARY
Data in neurological patients with disturbances in the bodily self suggest an important role of vestibular processes in global aspects of the self such as self-location and first-person perspective. We used mental imagery and multisensory bodily illusions to simulate aspects of such neurological conditions in healthy participants to investigate underlying functional and neural mechanisms. In these experiments both vestibular stimulation as well as visuo-vestibular conflicts interfered with global aspects of the self, confirming a contribution of vestibular processing to a stable sense of self, localized at a specific position in space with a single perspective on the world. Functional magnetic resonance imaging revealed that temporo-parietal junction (TPJ) activity reflected experimental changes in self-location and first-person perspective due to multisensory conflicts. This finding relates again to data in neurological patients that suggest integration of vestibular, somatosensory and visual signals in the TPJ are crucial for a stable sense of self.
Symposium 4: ch. Lopez
Friday, July 6 2012 14:00-16:00 @ Dome Theatre
Symposium 4: "Balancing the Self: Vestibular Contributions to Self-Consciousness"
Chair: Christophe Lopez (Centre National de la Recherche Scientifique, Université de Provence France)
SUMMARY
Introduction by Christophe Lopez.
Recent developments in cognitive neuroscience and philosophy of mind have highlighted some of the bodily foundations of the subjective experience of being a self (bodily self-consciousness). Yet, past research has focused on the convergence of visual, tactile and proprioceptive signals for aspects of bodily self-consciousness such as the sense of body ownership, self-identification, and self-location. However, recent work suggests a fundamental importance of vestibular signals for bodily self-consciousness. The fact that the vestibular system has been neglected until recently is surprising because this sensory system encodes one’s body position with respect to gravity as well as translations and rotations of the body in space. We will present data from cognitive neuroscience, neurology and neuroimaging showing the importance of the interactions of vestibular signals with visual and somatosensory signals to reflect bodily self-consciousness, including the first-person perspective. Bigna Lenggenhager will describe recent data on experimentally-induced changes in self-location and first-person perspective that were induced via visuo-vestibular and tactile conflicts. The importance of vestibular signals in perspective taking, self-other and self-environment distinctions will be discussed by Christophe Lopez. Gabriella Bottini will demonstrate the possibility to manipulate bodily consciousness, and various bodily deficits of neurological origin, using vestibular stimulation. The three speakers will discuss the convergence of vestibular signals in brain areas underpinning body representations. The convergence of the data presented during this symposium should stimulate the inclusion of vestibular signals into current models of body representations and pre-reflective forms of bodily self-consciousness.
Symposium 4: "Balancing the Self: Vestibular Contributions to Self-Consciousness"
Chair: Christophe Lopez (Centre National de la Recherche Scientifique, Université de Provence France)
SUMMARY
Introduction by Christophe Lopez.
Recent developments in cognitive neuroscience and philosophy of mind have highlighted some of the bodily foundations of the subjective experience of being a self (bodily self-consciousness). Yet, past research has focused on the convergence of visual, tactile and proprioceptive signals for aspects of bodily self-consciousness such as the sense of body ownership, self-identification, and self-location. However, recent work suggests a fundamental importance of vestibular signals for bodily self-consciousness. The fact that the vestibular system has been neglected until recently is surprising because this sensory system encodes one’s body position with respect to gravity as well as translations and rotations of the body in space. We will present data from cognitive neuroscience, neurology and neuroimaging showing the importance of the interactions of vestibular signals with visual and somatosensory signals to reflect bodily self-consciousness, including the first-person perspective. Bigna Lenggenhager will describe recent data on experimentally-induced changes in self-location and first-person perspective that were induced via visuo-vestibular and tactile conflicts. The importance of vestibular signals in perspective taking, self-other and self-environment distinctions will be discussed by Christophe Lopez. Gabriella Bottini will demonstrate the possibility to manipulate bodily consciousness, and various bodily deficits of neurological origin, using vestibular stimulation. The three speakers will discuss the convergence of vestibular signals in brain areas underpinning body representations. The convergence of the data presented during this symposium should stimulate the inclusion of vestibular signals into current models of body representations and pre-reflective forms of bodily self-consciousness.
Thursday, July 5, 2012
Symposium 3 Talk 4: Stazicker
Thursday, July 5 2012 14:00-16:00 @ Dome Theatre
Symposium 3: "Perceptual consciousness and cognitive access"
Talk 4: “Indeterminate perceptual consciousness and cognitive access”
James Stazicker (Department of Philosophy, New York University, USA)
SUMMARY
Does perceptual consciousness require cognitive access? Those who think it does often appeal to 'inattentional blindness' experiments to confirm their view. Those who think it doesn't often appeal to partial report experiments to confirm theirs. I'll argue that these experiments seem to provide this sort of evidence about perceptual consciousness and cognitive access, only because of an assumption about the determinacy of perceptual consciousness. To assess this assumption, we have to face up to a more ancient philosophical controversy about the difference between perception and cognition.
Symposium 3: "Perceptual consciousness and cognitive access"
Talk 4: “Indeterminate perceptual consciousness and cognitive access”
James Stazicker (Department of Philosophy, New York University, USA)
SUMMARY
Does perceptual consciousness require cognitive access? Those who think it does often appeal to 'inattentional blindness' experiments to confirm their view. Those who think it doesn't often appeal to partial report experiments to confirm theirs. I'll argue that these experiments seem to provide this sort of evidence about perceptual consciousness and cognitive access, only because of an assumption about the determinacy of perceptual consciousness. To assess this assumption, we have to face up to a more ancient philosophical controversy about the difference between perception and cognition.
Symposium 3 Talk 3: Sligte
Thursday, July 5 2012 14:00-16:00 @ Dome Theatre
Symposium 3: "Perceptual consciousness and cognitive access"
Talk 3: "Making perceptual consciousness accessible"
Ilja Gabriël Sligte (Department of Psychology, University of Amsterdam, The Netherlands)
SUMMARY
In recent years, we have published several papers showing the existence of a high-capacity (up to 15 objects) and long-lived (up to 4s) form of sensory memory that can be clearly dissociated from pure iconic memory (Sligte, Scholte, Lamme, 2008) and from working memory (Sligte, Wokke, Tesselaar, Scholte, & Lamme, 2010; Vandenbroucke, Sligte, & Lamme, 2011). However, all these results were based on partial-report experiments where subjects had to choose between change and no-change responses. This fact has triggered the criticism that subjects were just guessing (Phillips, 2011) on the basis of unconscious representations, as in blindsight. To explore this alternative explanation of our findings, we tested how subjects performed on a partial-report task with continuous response options (see Zhang & Luck, 2008; Bays & Husain, 2008 for examples of the task; we added retro-cues to this paradigm similar to Sligte, Scholte, & Lamme, 2008). We observed that subjects could report 7 objects (out of 10) with high precision on pure iconic memory conditions, about 6 on retro-cue (long-lasting and fragile form of iconic memory) conditions, and only 4 on postcue, working memory conditions. This suggests that all our previous studies validly make perceptual consciousness available for cognitive access.
Symposium 3: "Perceptual consciousness and cognitive access"
Talk 3: "Making perceptual consciousness accessible"
Ilja Gabriël Sligte (Department of Psychology, University of Amsterdam, The Netherlands)
SUMMARY
In recent years, we have published several papers showing the existence of a high-capacity (up to 15 objects) and long-lived (up to 4s) form of sensory memory that can be clearly dissociated from pure iconic memory (Sligte, Scholte, Lamme, 2008) and from working memory (Sligte, Wokke, Tesselaar, Scholte, & Lamme, 2010; Vandenbroucke, Sligte, & Lamme, 2011). However, all these results were based on partial-report experiments where subjects had to choose between change and no-change responses. This fact has triggered the criticism that subjects were just guessing (Phillips, 2011) on the basis of unconscious representations, as in blindsight. To explore this alternative explanation of our findings, we tested how subjects performed on a partial-report task with continuous response options (see Zhang & Luck, 2008; Bays & Husain, 2008 for examples of the task; we added retro-cues to this paradigm similar to Sligte, Scholte, & Lamme, 2008). We observed that subjects could report 7 objects (out of 10) with high precision on pure iconic memory conditions, about 6 on retro-cue (long-lasting and fragile form of iconic memory) conditions, and only 4 on postcue, working memory conditions. This suggests that all our previous studies validly make perceptual consciousness available for cognitive access.
Symposium 3 Talk 2: Sackur
Thursday, July 5 2012 14:00-16:00 @ Dome Theatre
Symposium 3: "Perceptual consciousness and cognitive access"
Talk 2: “Kinds of access and phenomenality”
Jérôme Sackur (Department of Cognitive Studies, Ecole Normale Supérieure, France)
SUMMARY
The science of consciousness seems to face a recurrent dilemma: either accept a non fully reportable phenomenal quality of conscious contents or repudiate phenomenality altogether. In this talk I will argue that this dilemma seems to arise only because of the delusive simplicity of the notion of cognitive access. I will show that access is more diverse than commonly acknowledged, and that it can be probed in many ways. Cognitive access is not uniform: for one given stimulus, it may vary in completeness, and also in regards to levels of processing. Therefore, any report of a conscious state must integrate an array of disparate fragments of accessed information, and take into account prior knowledge of the context. I argue that with this richer notion of access, we can aim for a functional construal of consciousness which obviates the need for a special kind of phenomenal consciousness.
Symposium 3: "Perceptual consciousness and cognitive access"
Talk 2: “Kinds of access and phenomenality”
Jérôme Sackur (Department of Cognitive Studies, Ecole Normale Supérieure, France)
SUMMARY
The science of consciousness seems to face a recurrent dilemma: either accept a non fully reportable phenomenal quality of conscious contents or repudiate phenomenality altogether. In this talk I will argue that this dilemma seems to arise only because of the delusive simplicity of the notion of cognitive access. I will show that access is more diverse than commonly acknowledged, and that it can be probed in many ways. Cognitive access is not uniform: for one given stimulus, it may vary in completeness, and also in regards to levels of processing. Therefore, any report of a conscious state must integrate an array of disparate fragments of accessed information, and take into account prior knowledge of the context. I argue that with this richer notion of access, we can aim for a functional construal of consciousness which obviates the need for a special kind of phenomenal consciousness.
Symposium 3 Talk 1: Block
Thursday, July 5 2012 14:00-16:00 @ Dome Theatre
Symposium 3: "Perceptual consciousness and cognitive access"
Talk 1: "The fundamental methodological problem of consciousness research"
Ned Block (Departments of Philosophy, Psychology and Center for Neural Science, New York University, USA)
SUMMARY
Theories of consciousness are ultimately based on what we and other people report (or better: think) about their conscious states in various experimental paradigms. Some approaches—mine for example—claim that on the basis of such evidence we can conclude that cosciousness is richer than cognitive access and in particular there are experimental setups where inevitably reports and other cognitive processes will not reflect all of the specific details of conscious experience. But how can we know about the unaccessed conscious detail when being unaccessed would seem to preclude such knowledge? A similar problem arises in knowing about the conscious experience of unattended stimuli, since reporting requires attention to the stimuli or to memory traces of them, and attention is known to alter conscious experience. This talk proposes a solution to this problem.
Symposium 3: "Perceptual consciousness and cognitive access"
Talk 1: "The fundamental methodological problem of consciousness research"
Ned Block (Departments of Philosophy, Psychology and Center for Neural Science, New York University, USA)
SUMMARY
Theories of consciousness are ultimately based on what we and other people report (or better: think) about their conscious states in various experimental paradigms. Some approaches—mine for example—claim that on the basis of such evidence we can conclude that cosciousness is richer than cognitive access and in particular there are experimental setups where inevitably reports and other cognitive processes will not reflect all of the specific details of conscious experience. But how can we know about the unaccessed conscious detail when being unaccessed would seem to preclude such knowledge? A similar problem arises in knowing about the conscious experience of unattended stimuli, since reporting requires attention to the stimuli or to memory traces of them, and attention is known to alter conscious experience. This talk proposes a solution to this problem.
Symposium 3: ch. Block
Thursday, July 5 2012 14:00-16:00 @ Dome Theatre
Symposium 3: "Perceptual consciousness and cognitive access"
Chair: Ned Block (Departments of Philosophy, Psychology and Center for Neural Science, New York University, USA)
SUMMARY
Introduction by Ned Block
The most basic issue concerning the foundations of conscious perception is whether perceptual consciousness is rich or sparse. The overflow argument uses a form of iconic memory to argue that perceptual consciousness is rich, i.e. has a higher capacity than cognitive access: we are conscious of more than we can report or think about. However, there is also evidence that iconic memory is fragmentary and that it may involve “gists” or generic representations. These points have been used to argue that the informational resources that are the basis of “partial report superiority” in iconic memory experiments are really unconscious, and so the overflow argument is mistaken. A further alternative is that the debate between rich and sparse views of perception is not empirically decideable. This issue is one of the most thoroughly interdisciplinary of all theoretical issues concerning consciousness and accordingly this symposium has two philosophers and two scientists.
Symposium 3: "Perceptual consciousness and cognitive access"
Chair: Ned Block (Departments of Philosophy, Psychology and Center for Neural Science, New York University, USA)
SUMMARY
Introduction by Ned Block
The most basic issue concerning the foundations of conscious perception is whether perceptual consciousness is rich or sparse. The overflow argument uses a form of iconic memory to argue that perceptual consciousness is rich, i.e. has a higher capacity than cognitive access: we are conscious of more than we can report or think about. However, there is also evidence that iconic memory is fragmentary and that it may involve “gists” or generic representations. These points have been used to argue that the informational resources that are the basis of “partial report superiority” in iconic memory experiments are really unconscious, and so the overflow argument is mistaken. A further alternative is that the debate between rich and sparse views of perception is not empirically decideable. This issue is one of the most thoroughly interdisciplinary of all theoretical issues concerning consciousness and accordingly this symposium has two philosophers and two scientists.
Symposium 2 Talk 3: Tsakiris
Thursday, July 5 2012 11:00-13:00 @ Dome Theatre
Symposium 2: "Bringing the in-depth body to the surface: interoception, awareness and prediction"
Talk 3: "Just a heartbeat away from one’s body: interoceptive sensitivity and malleability of self-representations"
Manos Tsakiris (University of London, UK)
SUMMARY
Body-awareness relies on the representation of both interoceptive and exteroceptive percepts coming from one’s body. However, the exact relationship and possible interaction of interoceptive and exteroceptive systems for body-awareness remain unknown. Based on recent models of self-awareness that consider the insula as a convergence zone linked to the representation of the bodily self, we examined the interaction between interoceptive and exteroceptive awareness of the body. Across three experiments, we combined measures of interoceptive sensitivity with experimental manipulations of body representations. Consistent results suggests that interoceptive sensitivity predicts the malleability of body representations, that is, people with low interoceptive sensitivity experience stronger illusions of embodiment (“rubber hand illusion”) and identification (“enfacement illusion”). In one final experiment, we manipulated interoceptive sensitivity by mirror self-observation. Overall these findings suggest that interoceptive sensitivity modulates the integration of multisensory information and predicts the strength of self-representations.
Symposium 2: "Bringing the in-depth body to the surface: interoception, awareness and prediction"
Talk 3: "Just a heartbeat away from one’s body: interoceptive sensitivity and malleability of self-representations"
Manos Tsakiris (University of London, UK)
SUMMARY
Body-awareness relies on the representation of both interoceptive and exteroceptive percepts coming from one’s body. However, the exact relationship and possible interaction of interoceptive and exteroceptive systems for body-awareness remain unknown. Based on recent models of self-awareness that consider the insula as a convergence zone linked to the representation of the bodily self, we examined the interaction between interoceptive and exteroceptive awareness of the body. Across three experiments, we combined measures of interoceptive sensitivity with experimental manipulations of body representations. Consistent results suggests that interoceptive sensitivity predicts the malleability of body representations, that is, people with low interoceptive sensitivity experience stronger illusions of embodiment (“rubber hand illusion”) and identification (“enfacement illusion”). In one final experiment, we manipulated interoceptive sensitivity by mirror self-observation. Overall these findings suggest that interoceptive sensitivity modulates the integration of multisensory information and predicts the strength of self-representations.
Symposium 2 Talk 2: Hopkins
Thursday, July 5 2012 11:00-13:00 @ Dome Theatre
Symposium 2: "Bringing the in-depth body to the surface: interoception, awareness and prediction"
Talk 2: “Interoception and the Problem of Consciousness”
Jim Hopkins (Department of Philosophy, King’s College, UK)
SUMMARY
Recent studies have shown that “unconscious” processing can be surprisingly powerful (cf work in the labs of Lamme, Dijksterhuis, Mattler, Haynes, Dehaene, Bargh, myself, etc). I had taken these results to be a challenge to the notion that sensory awareness has special functional power. Here I criticize my previous arguments. A useful analogy: People without legs can move around (albeit poorly), but we all agree that legs are for locomotion. Likewise, although certain higher cognitive functions can be performed without awareness (just barely better than chance), it does not mean that awareness has no functional advantage. A different approach is to create conditions where subjects are equally good at detecting and discriminating the stimulus, but they report different subjective levels of awareness. Under these performance capacity‐matched cases, we observed functional advantage for awareness only in some specific tasks. These results give powerful constraints for theorizing about sensory awareness in general.
Symposium 2: "Bringing the in-depth body to the surface: interoception, awareness and prediction"
Talk 2: “Interoception and the Problem of Consciousness”
Jim Hopkins (Department of Philosophy, King’s College, UK)
SUMMARY
Recent studies have shown that “unconscious” processing can be surprisingly powerful (cf work in the labs of Lamme, Dijksterhuis, Mattler, Haynes, Dehaene, Bargh, myself, etc). I had taken these results to be a challenge to the notion that sensory awareness has special functional power. Here I criticize my previous arguments. A useful analogy: People without legs can move around (albeit poorly), but we all agree that legs are for locomotion. Likewise, although certain higher cognitive functions can be performed without awareness (just barely better than chance), it does not mean that awareness has no functional advantage. A different approach is to create conditions where subjects are equally good at detecting and discriminating the stimulus, but they report different subjective levels of awareness. Under these performance capacity‐matched cases, we observed functional advantage for awareness only in some specific tasks. These results give powerful constraints for theorizing about sensory awareness in general.
Symposium 2 Talk 1: Critchley
Thursday, July 5 2012 11:00-13:00 @ Dome Theatre
Symposium 2: "Bringing the in-depth body to the surface: interoception, awareness and prediction"
Talk 1: "Visceral afferent signaling, interoceptive awareness and predictive coding: Impact on emotional processes"
Hugo Critchley (Sackler Centre for Consciousness Science, Department of Psychiatry, Brighton and Sussex Medical School, UK)
SUMMARY
The experience of emotions as subjective feeling states arguably reflects the cognitive appraisal of information about changes in bodily state in conjunction with the inferences about the causes of those changes, consistent with a predictive coding framework. Moreover, individual differences in physiological responsivity influence the experience of emotions and people can be categorized according to their accuracy in judging physiological processes including heartbeats. Studies of good and bad 'heartbeat detectors' confirm a relationship between enhanced interoceptive ability and intensity of emotional experiences. Mechanistically, central signalling of cardiovascular arousal occurs via the activation of baroreceptors at cardiac systole that signals the occurrence and amplitude of individual heartbeats. We have shown this interoceptive stream differentially influences automatic processing and intentional evaluation of emotional stimuli including facial expressions. Nevertheless, cognitive and physiological dimensions of interoception can be dissociated experimentally, endorsing a model of interoceptive predictive coding which we have recently developed.
Symposium 2: "Bringing the in-depth body to the surface: interoception, awareness and prediction"
Talk 1: "Visceral afferent signaling, interoceptive awareness and predictive coding: Impact on emotional processes"
Hugo Critchley (Sackler Centre for Consciousness Science, Department of Psychiatry, Brighton and Sussex Medical School, UK)
SUMMARY
The experience of emotions as subjective feeling states arguably reflects the cognitive appraisal of information about changes in bodily state in conjunction with the inferences about the causes of those changes, consistent with a predictive coding framework. Moreover, individual differences in physiological responsivity influence the experience of emotions and people can be categorized according to their accuracy in judging physiological processes including heartbeats. Studies of good and bad 'heartbeat detectors' confirm a relationship between enhanced interoceptive ability and intensity of emotional experiences. Mechanistically, central signalling of cardiovascular arousal occurs via the activation of baroreceptors at cardiac systole that signals the occurrence and amplitude of individual heartbeats. We have shown this interoceptive stream differentially influences automatic processing and intentional evaluation of emotional stimuli including facial expressions. Nevertheless, cognitive and physiological dimensions of interoception can be dissociated experimentally, endorsing a model of interoceptive predictive coding which we have recently developed.
Symposium 2: ch. Tsakiris
Thursday, July 5 2012 11:00-13:00 @ Dome Theatre
Symposium 2: "Bringing the in-depth body to the surface: interoception, awareness and prediction"
Chair: Manos Tsakiris (Department of Psychology, University of London, UK)
SUMMARY
Introduction by Manos Tsakiris.
Interoception is a ubiquitous information channel used for the central representation of internal bodily states. A renewed interest in the functional role of interoception has emphasized its primary role for the representation of an integrated sense of self. At the same time, current models of perception have been largely influenced by a Bayesian approach that underlines the role of internal predictive models for the processing and interpretation of incoming exteroceptive information. Could the functional role of interoception be understood in terms of predictive coding, and if yes what are the implications for interoceptive awareness? Interoceptive awareness (i.e. the awareness of the physiological state of one’s body) is assessed by quantifying interoceptive sensitivity (IS), usually in the context of heartbeat detection tasks. Behaviourally, the sensitivity to the perception of internal states of the body has been shown to modulate a range of cognitive, affective and sensory processes. The three talks of this symposium will focus on how sensitivity to internal bodily states comes to awareness and how it modulates emotional processes (Critchley), self-other representations (Tsakiris) and internal conflicts (Hopkins) via predictive internal models. Across three disciplines (e.g. neuroscience, psychology and philosophy), the three talks provide a timely debate of interoception as a model of predictive coding.
Symposium 2: "Bringing the in-depth body to the surface: interoception, awareness and prediction"
Chair: Manos Tsakiris (Department of Psychology, University of London, UK)
SUMMARY
Introduction by Manos Tsakiris.
Interoception is a ubiquitous information channel used for the central representation of internal bodily states. A renewed interest in the functional role of interoception has emphasized its primary role for the representation of an integrated sense of self. At the same time, current models of perception have been largely influenced by a Bayesian approach that underlines the role of internal predictive models for the processing and interpretation of incoming exteroceptive information. Could the functional role of interoception be understood in terms of predictive coding, and if yes what are the implications for interoceptive awareness? Interoceptive awareness (i.e. the awareness of the physiological state of one’s body) is assessed by quantifying interoceptive sensitivity (IS), usually in the context of heartbeat detection tasks. Behaviourally, the sensitivity to the perception of internal states of the body has been shown to modulate a range of cognitive, affective and sensory processes. The three talks of this symposium will focus on how sensitivity to internal bodily states comes to awareness and how it modulates emotional processes (Critchley), self-other representations (Tsakiris) and internal conflicts (Hopkins) via predictive internal models. Across three disciplines (e.g. neuroscience, psychology and philosophy), the three talks provide a timely debate of interoception as a model of predictive coding.
Tuesday, July 3, 2012
Symposium 1 Talk 3: Brown
Tuesday, July 3 2012 11:00-13:00 @ Dome Theatre
Symposium 1: "Consciousness fading"
Talk 3: “The neural dynamics of loss and recovery of consciousness under general anesthesia”
Emery Brown (Department of Anesthesia, Harvard Medical School, USA)
SUMMARY
General anesthesia is a drug-induced, reversible condition comprised of five behavioral states: unconsciousness, amnesia (loss of memory), analgesia (loss of pain sensation), akinesia (immobility), and hemodynamic stability with control of the stress response. The mechanisms by which anesthetic drugs induce the state of general anesthesia are considered one of the biggest mysteries of modern medicine. We have been using three experimental paradigms to study general anesthesia-induced loss of consciousness in humans: combined fMRI/EEG recordings, high-density EEG recordings and intracranial recordings. These studies are allowing us to establish precise neurophysiological, neuroanatomical and behavioral correlates of unconsciousness under general anesthesia. Combined with our mathematical modeling work on how anesthetics act on neural circuits to produce the state of general anesthesia we are able to offer specific hypotheses as to how changes in level of activity in specific circuits lead to the unconscious state. We will discuss the relation between our findings and two other important altered states of arousal: sleep and coma. Our findings suggest that the state of general anesthesia is not as mysterious as currently believed.
Symposium 1: "Consciousness fading"
Talk 3: “The neural dynamics of loss and recovery of consciousness under general anesthesia”
Emery Brown (Department of Anesthesia, Harvard Medical School, USA)
SUMMARY
General anesthesia is a drug-induced, reversible condition comprised of five behavioral states: unconsciousness, amnesia (loss of memory), analgesia (loss of pain sensation), akinesia (immobility), and hemodynamic stability with control of the stress response. The mechanisms by which anesthetic drugs induce the state of general anesthesia are considered one of the biggest mysteries of modern medicine. We have been using three experimental paradigms to study general anesthesia-induced loss of consciousness in humans: combined fMRI/EEG recordings, high-density EEG recordings and intracranial recordings. These studies are allowing us to establish precise neurophysiological, neuroanatomical and behavioral correlates of unconsciousness under general anesthesia. Combined with our mathematical modeling work on how anesthetics act on neural circuits to produce the state of general anesthesia we are able to offer specific hypotheses as to how changes in level of activity in specific circuits lead to the unconscious state. We will discuss the relation between our findings and two other important altered states of arousal: sleep and coma. Our findings suggest that the state of general anesthesia is not as mysterious as currently believed.
Symposium 1 Talk 2: Boly
Tuesday, July 3 2012 11:00-13:00 @ Dome Theatre
Symposium 1: "Consciousness fading"
Talk 2: “Is propofol-induced loss of consciousness a sleep-like state?”
Melanie Boly (Coma Science Group, University of Liege, Belgium)
SUMMARY
Mechanisms of propofol-induced fading of consciousness, as well as the relationship between propofol anesthesia and sleep remains poorly understood. We will review recent neuroimaging studies investigating neural correlates of loss of consciousness during propofol sedation and non-REM sleep. We will then highlight some commonalities as well as observed differences in terms of spontaneous EEG, or functional and effective connectivity (using high-density EEG, functional MRI or TMS-EEG) between propofol and non-REM sleep. Finally, we will discuss the implications of these results for neural correlates of consciousness and for their use as clinical tools to detect awareness during anesthesia, and in other altered consciousness states.
Symposium 1: "Consciousness fading"
Talk 2: “Is propofol-induced loss of consciousness a sleep-like state?”
Melanie Boly (Coma Science Group, University of Liege, Belgium)
SUMMARY
Mechanisms of propofol-induced fading of consciousness, as well as the relationship between propofol anesthesia and sleep remains poorly understood. We will review recent neuroimaging studies investigating neural correlates of loss of consciousness during propofol sedation and non-REM sleep. We will then highlight some commonalities as well as observed differences in terms of spontaneous EEG, or functional and effective connectivity (using high-density EEG, functional MRI or TMS-EEG) between propofol and non-REM sleep. Finally, we will discuss the implications of these results for neural correlates of consciousness and for their use as clinical tools to detect awareness during anesthesia, and in other altered consciousness states.
Symposium 1 Talk 1: Supp
Tuesday, July 3 2012 11:00-13:00 @ Dome Theatre
Symposium 1: "Consciousness fading"
Talk 1: "Block of intracortical communication by propofol-induced neural hypersynchy"
Gernot Supp (Dept. of Neurophysiology and Pathophysiology University Medical Center, Hamburg, Germany)
SUMMARY
Manipulating consciousness by anesthetic agents is everyday clinical practice. However, the key mechanisms underlying pharmacologically induced breakdown of consciousness are still largely unresolved. Unraveling the neural determinants of loss of consciousness, apart from its obvious medical advances, may shed new light on brain processes relevant for the emergence of consciousness. The presentations of this symposium will discuss complementary findings that suggest convergent conclusions and highlight the implications of anesthesia research for understanding the neural mechanisms of consciousness. The first and the second presentation will focus on propofol anesthesia as a model of drug-induced loss of consciousness, and discuss recent experimental evidence suggesting that propofol anesthesia induces hypersynchronous ongoing activity leading to a brain state during which information processing is severely compromised, and functional integration across different areas is strongly reduced. The second presentation will also highlight potential similarities between the neurophysiological changes induced by propofol and those observed during sleep. The third presentation of the symposium will, in addition to discussing recent modeling work on the mechanisms of propofol anesthesia, provide a broader framework for understanding changes in neural dynamics under general anesthesia.
Symposium 1: "Consciousness fading"
Talk 1: "Block of intracortical communication by propofol-induced neural hypersynchy"
Gernot Supp (Dept. of Neurophysiology and Pathophysiology University Medical Center, Hamburg, Germany)
SUMMARY
Manipulating consciousness by anesthetic agents is everyday clinical practice. However, the key mechanisms underlying pharmacologically induced breakdown of consciousness are still largely unresolved. Unraveling the neural determinants of loss of consciousness, apart from its obvious medical advances, may shed new light on brain processes relevant for the emergence of consciousness. The presentations of this symposium will discuss complementary findings that suggest convergent conclusions and highlight the implications of anesthesia research for understanding the neural mechanisms of consciousness. The first and the second presentation will focus on propofol anesthesia as a model of drug-induced loss of consciousness, and discuss recent experimental evidence suggesting that propofol anesthesia induces hypersynchronous ongoing activity leading to a brain state during which information processing is severely compromised, and functional integration across different areas is strongly reduced. The second presentation will also highlight potential similarities between the neurophysiological changes induced by propofol and those observed during sleep. The third presentation of the symposium will, in addition to discussing recent modeling work on the mechanisms of propofol anesthesia, provide a broader framework for understanding changes in neural dynamics under general anesthesia.
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