Tutorials

Morning tutorial descriptions

 

Tutorial 1: The Scope and Limits of Brain Imaging in Consciousness Research

Hakwan Lau Department of Experimental Psychology, Oxford University Wellcome Department of Imaging Neuroscience, University College London

Brain imaging has gained a lot of attention within the consciousness research community. The aim of this workshop is to give a non-technical (i.e. no equations) introduction to brain imaging, allowing non-experts to be able to read and understand experimental reports critically. First I explain the basic procedures and mechanisms of how a typical fMRI or PET study is done, and how the data are analyzed. I then focus on the methodological problems that are often found in published articles, such as statistical errors and anatomical mis-localization. The results in imaging often depend on how the data were analyzed, and therefore a cautious reading of the methodology is necessary. I then move on to discuss issues of interpretation using examples from the consciousness research literature. I particularly pick out cases where theoretical interpretations of brain imaging results were misguided, and explain why some forms of arguments are fallacious. For example, the fact that two tasks reveal similar activations in the same brain region does not necessarily mean that they are fundamentally related; there are only so many brain regions defined by conventional labels. I then describe some more advanced methods that bypass the problems discussed. These include repetitional priming, connectivity analyses, high-resolution imaging and multivariate approaches. Finally I also describe other relatively new techniques such as MEG and fMRI-guided TMS and discuss how they might contribute to consciousness research in the future.



Tutorial 2: Representing and misrepresenting the body

Frederique de Vignemont Institut of Cognitive Science Roblin Meeks Princeton University

What neural subsystems are implicated in representing one’s body? Do we draw upon the same subsystem to represent the bodies of others? How sensitive are such representations to input from different sensory modalities? What underwrites or constitutes our sense of bodily ownership, the feeling we have that we experience a particular body “from the inside”? In this workshop we investigate the central questions surrounding the ways in which we represent and misrepresent our bodies in thought and action. We canvas recent work in both philosophy and psychology, paying particular attention to neuropsychological data concerning disruptions in body representations such as asomatognosia and autotopagnosia and the susceptibility of normal subjects to illusions of limb ownership. We end with considerations as to how philosophical theories of conscious experience of our bodies can both inform and be informed by empirical data.



Tutorial 3: Reading conscious and unconscious mental states from human brain activity

John-Dylan Haynes Bernstein Center for Computational Neuroscience Berlin

Recent advances in human neuroimaging have shown that it is possible to accurately “read” or “decode” a person's conscious experience from non-invasive measurements of their brain activity. Such decoding is based on the idea that each thought is associated with a unique spatial pattern of brain activity. By training a computer to recognize these unique patterns it is possible to reliably read many different thoughts from a person’s brain activity. This tutorial will give a broad overview of the emerging field of “brain reading”, as well as an in-depth discussion of its implications for research on consciousness. The first section will provide a historical overview of brain reading with a special focus on EEG. The second section will concisely present the main brain imaging techniques used for brain reading (EEG, single- and multi-cell recordings, fMRI). The third section will introduce the key concepts of information theory and pattern recognition in an easily accessible form. The fourth section will present an overview of the current “state of the art” in the field including many examples. The fifth section will show in-depth all steps involved in a typical brain-reading study. For this purpose a study will be presented step-by-step that tracks a dynamically changing “stream of consciousness” using fMRI. A sixth section will demonstrate how decoding-based research can provide important clues about conscious and unconscious information processing, and how it is a useful framework for studying neural “representation” in general. Finally, the current challenges and limitations of brain reading techniques will be discussed along with perspectives for future research.



Tutorial 4: Can inner experience be faithfully described?

Russell T. HurlburtPsychology,University of Nevada, Las VegasEric SchwitzgebelPhilosophy, University of California, Riverside

Psychologist Russell Hurlburt is known for his innovative methods of exploring inner experience. Philosopher Eric Schwitzgebel is known for his skepticism about such methods. Hurlburt and Schwitzgebel will team up (perhaps “square off” would be a better term) and interview two subjects selected from the ASSC membership about the details of their inner experience. That interview will follow Hurlburt’s Descriptive Experience Sampling (DES) method: the subjects will have taken DES random beepers into their natural environments and paid attention to whatever experiences were ongoing at the moments of a half-dozen random beeps. Hurlburt, Schwitzgebel, and the tutorial attendees will question the subjects about those beeps during what DES calls the “expositional interview.” During these interviews, we (all tutorial participants) will conduct “sidebar” discussions about: what are the characteristics of good and bad questions; how believable are the subjects’ reports; to what extent do we “lead the witness”; etc.

Tutorial 4 attendees: Would you like be a subject in this demonstration? If so, visit http://www.nevada.edu/~russ/assc-demo-participants.html

 

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.