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June 22-25, 2007, Imperial Palace Hotel, Las Vegas

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Afternoon Tutorial Descriptions


Tutorial 5: The Pharmacology of Perception

Olivia Carter Vision Sciences Lab, Psychology Dept,Harvard UniversityMichael SilverHelen Wills Neuroscience Institute and School of Optometry,University of California, Berkeley

Pharmacological studies have proven to be invaluable to molecular, cellular, and systems neuroscientists in the study of neurons and neural networks. The benefits of being able to experimentally manipulate complex systems in a biochemically-specific manner are well-established in these fields. However, pharmacology has rarely been employed in the study of perception, cognition, or consciousness. This tutorial will show how pharmacological research can provide critical information regarding the neurotransmitters that modulate consciousness as well as providing insights into the neural correlates of consciousness itself. Specifically, we will explore the pharmacology of perception in three sections that will be accessible to nonscientists but also be detailed enough to give the most experienced neuroscientist plenty to think about. The three sections will include 1) Introduction to neuropharmacology, from receptor biochemistry to the cognitive functions of the major neurotransmitter systems. 2) The role of serotonin (5-HT) in visual perception. We will review a number of experiments indicating a special role for the cortical 5 HT2A receptor in the action of hallucinogenic drugs. Data will also be presented from human behavioral studies examining the effects of psilocybin (the 5-HT2A activating drug found in magic mushrooms) on visual perception and attention. 3) The role of acetylcholine in cognition, including learning, memory, and attention. Behavioral and neuroimaging results from cholinergic pharmacology studies in humans will be discussed, including studies of attention and visual perception.


Tutorial 6: What is self-specific? A tutorial questioning the cerebral correlates of the self

Dorothée Legrand (Chair)CREA, Centre de Recherche en Epistémologie Appliquée.Perrine Ruby (Chair)Centre hospitalier Le Vinatier

The self is increasingly investigated empirically. However, reviews show that the self still lacks both consensual definition and specific cerebral correlates. This tutorial intends to better understand and overcome this critical situation.

First (Dorothée Legrand), two criteria for self-specificity will be determined: Exclusivity (X applies only to the self) and Collinearity (Any change of X entails a change of the self). These criteria are met neither by evaluative processing nor by self-attributed contents, but by first-person perspective. The latter relates represented objects to the representing subject without depending on any representation of the self. It is proposed that such relation is made possible at a basic level thanks to a sensori-motor integration i.e. the matching of efference with re-afference (afference issuing from the subject's own action) Self-specificity will thus be accounted for in functional terms, in a framework integrating a dynamic sensorimotor approach and a phenomenological account of bodily self-consciousness.

Second (Perrine Ruby), a review of the neuroimaging literature will come in support to this theoretical proposal. A synthesis of a wide range of neuroimaging studies tackling self, mind reading, memory, reasoning and resting state issues will serve to demonstrate that the cerebral activations repeatedly reported in self-related studies are also recruited for others-related tasks. It is argued that such common cerebral network can thus not subserve any self-specific component, but would rather subserve a general cognitive processing of evaluation using information recalled from memory, which would explain its recruitment in all the aforementionned tasks. The search of the self is thus re-oriented toward the self-specific first-person perspective. Results of the literature showing increased activity in somatosensory-related corticies for first (vs third) person perspective coheres with the theoretical proposal that the first-person perspective is grounded on
sensorimotor integration and encourage further invesigations in this direction.


Tutorial 7: The relationship between top-down attention and consciousness

Naotsugu Tsuchiya and Christof Koch California Institute of Technology

Historically, the pervading assumption among sensory psychologists is that what a subject attends to is what she is conscious of. That is, attention and consciousness are very closely related, if not identical, processes. However, a number of recent authors have argued that these are two distinct processes, with different neuronal mechanisms. While the neuronal correlates of consciousness remain elusive, significant progress has been made in studying the neuronal correlates of “unconscious” processing; a multitude of techniques---such as masking, crowding, attentional blink, motion-induced blindness, continuous flash-suppression, and binocular rivalry---permit visual scenes to be presented to subjects without subjects becoming aware of them. Such experiments, coupled to fMRI in humans and single-cell recordings in behaving monkeys, show that vigorous hemodynamic and spiking activity in cortex is often not associated with conscious perception.

Building upon the successful tutorial at ASSC10, we review and update the recent evidence showing 1) that invisible stimuli can be attended with top-down attention and can influence subsequent behavior, 2) that to observe some behavioral evidence of unconscious processing, top-down attention to invisible stimuli is necessary and 3) that under some conditions top-down attention and consciousness can result in opposite effects.

The philosopher Ned Block has argued on conceptual grounds for two forms of consciousness, access (A) and phenomenal (P) consciousness. Given the data, it may be possible that A is equivalent to top-down attention and read-out (which usually, but not always, goes hand-in-hand with P) while P can occur with or without top-down attention.


Tutorial 8: “Measuring consciousness”: Combining objective and subjective data, and what it may all mean

Axel Cleeremans Cognitive Science Research Unit, Department of Psychology, Université Libre de Bruxelles
Morten Overgaard Neuropsychological Laboratory,Hammel Neurorehabilitation and Research Center
Andreas K. EngelDept. of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf

Can we measure consciousness? Does the question even make sense? On the one hand, any empirical approach to consciousness would seem to require that the concept be sufficiently well defined that we can indeed measure it, just as we can measure energy, mass, or reaction time. On the other, many would disagree with the very idea that consciousness is something that one can “measure”, as we have no direct way of assessing its presence in others In light of this quandary, it has been pointed out that consciousness presents unique methodological challenges for its study requires that one combines subjective (“first-person”) and objective (“third-person”) data. While some of these methods are familiar, many others have been proposed recently, and some have not been thoroughly explored yet. The main goal of this tutorial is to overview the different methods one can deploy to contrast information processing with and without consciousness. Many such methods are inherently interdisciplinary, and the tutorial will therefore highlight complementary methods ranging (1) from neuroimaging to introspection, (2) from methods appropriate to study normal cognition to methods best applied to patients, (3) from methods aimed at characterizing states or levels of consciousness to methods aimed at appreciating its contents and dynamics. In all three cases, we will focus specifically on how to best combine subjective and objective data, as well as on metatheoretical issues, such as the problem of bias in subjective methods or the problem of spurious correlations between performance and consciousness in imaging studies. The tutorial will be illustrated with recent experimental data.




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