The Neurology of Consciousness: Cognitive Neuroscience and Neuropathology This page intentionally left blank The Neurology of Consciousness: Cognitive Neuroscience and Neuropathology Edited by Steven Laureys and Giulio Tononi AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Academic Press is an imprint of Elsevier Academic Press is an imprint of Elsevier 32 Jamestown Road, London NW1 7BY, UK 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA 525 B Street, Suite 1900, San Diego, CA 92101-4495, USA First edition 2009 Copyright © 2009 Elsevier Ltd. 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Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress ISBN: 978-0-12-374168-4 For information on all Academic Press publications visit our website at www.books.elsevier.com Typeset by Charon Tec Ltd (A Macmillan Company), Chennai, India www.charontec.com. Printed and bound in China 09 10 10 9 8 7 6 5 4 3 2 1 To our families and loved ones; to our students, fellows and teachers. This page intentionally left blank Contents Preface ix Prologue xi List of Contributors xiii Section I: Basics 1 1. Consciousness: An Overview of the Phenomenon and of Its Possible Neural Basis 3 Antonio Damasio and Kaspar Meyer 2. The Neurological Examination of Consciousness 15 Hal Blumenfeld 3. Functional Neuroimaging 31 Steven Laureys, Melanie Boly and Giulio Tononi 4. Consciousness and Neuronal Synchronization 43 Wolf Singer 5. Neural Correlates of Visual Consciousness 53 Geraint Rees 6. The Relationship Between Consciousness and Attention 63 Naotsugu Tsuchiya and Christof Koch Section II: Waking, Sleep and Anaesthesia 79 7. Intrinsic Brain Activity and Consciousness 81 Marcus E. Raichle and Abraham Z. Snyder 8. Sleep and Dreaming 89 Giulio Tononi 9. Sleepwalking (Somnambulism): Dissociation Between ‘ Body Sleep ’ and ‘ Mind Sleep ’ 108 Claudio L. Bassetti 10. General Anaesthesia and Consciousness 118 Michael T. Alkire Section III: Coma and Related Conditions 135 11. Coma 137 G. Bryan Young 12. Brain Death 151 James L. Bernat vii viii CONTENTS 13. The Assessment of Conscious Awareness in the Vegetative State 163 Adrian M. Owen, Nicholas D. Schiff and Steven Laureys 14. The Minimally Conscious State: Clinical Features, Pathophysiology and Therapeutic Implications 173 Joseph T. Giacino and Nicholas D. Schiff 15. Consciousness in the Locked-in Syndrome 191 Olivia Gosseries, Marie-Aurélie Bruno, Audrey Vanhaudenhuyse, Steven Laureys and Caroline Schnakers 16. Consciousness and Dementia: How the Brain Loses Its Self 204 Pietro Pietrini, Eric Salmon and Paolo Nichelli 17. Brain–Computer Interfaces for Communication in Paralysed Patients and Implications for Disorders of Consciousness 217 Andrea Kübler 18. Neuroethics and Disorders of Consciousness: A Pragmatic Approach to Neuropalliative Care 234 Joseph J. Fins Section IV: Seizures, Splits, Neglects and Assorted Disorders 245 19. Epilepsy and Consciousness 247 Hal Blumenfeld 20. The Left Hemisphere Does Not Miss the Right Hemisphere 261 Michael S. Gazzaniga and Michael B. Miller 21. Visual Consciousness: An Updated Neurological Tour 271 Lionel Naccache 22. The Neurophysiology of Self-awareness Disorders in Conversion Hysteria 282 Patrik Vuilleumier 23. Leaving Body and Life Behind: Out-of-Body and Near-Death Experience 303 Olaf Blanke and Sebastian Dieguez 24. The Hippocampus, Memory, and Consciousness 326 Bradley R. Postle 25. Syndromes of Transient Amnesia 339 Chris Butler and Adam Zeman 26. Consciousness and Aphasia 352 Paolo Nichelli 27. Blindness and Consciousness: New Light from the Dark 360 Pietro Pietrini, Maurice Ptito and Ron Kupers 28. The Neurology of Consciousness: An Overview 375 Giulio Tononi and Steven Laureys Index 413 Preface T hinking must never submit itself, neither to a dogma, in engineering led to space observatories such as the nor to a party, nor to a passion, nor to an interest, nor Hubble Telescope to shed light on where we come to a preconceived idea, nor to anything whatsoever, from. Rigorous scientific measurements permitted to except to the facts themselves, because for it to submit trace back the birth of the universe to nearly 14.000 to anything else would be the end of its existence. million years; the age of the earth to more than 4.500 Henri Poincaré (1854–1912; million years; the origin of life on earth to (very) French mathematician and theoretical physicists) approximately 3.500 million years and the apparition of the earth’s first simple animals to about 600 mil- ‘ Truth is sought for its own sake. And those who lion years. Natural evolution, as brilliantly revealed are engaged upon the quest for anything for its own by Charles Darwin (1809–1882), over these many mil- sake are not interested in other things. Finding the lion years gave rise to nervous systems as complex as truth is difficult, and the road to it is rough. ’ wrote the human brain, arguably the most complex object in Ibn al-Haytham (965–1039; Persian polymath), a pio- the universe. And somehow, through the interactions neer of the scientific method. This book tackles one among its 100 billion neurons, connected by trillions of the biggest challenges of science; understanding of synapses, emerges our conscious experience of the the biological basis of human consciousness. It does world and of ourselves. so through observation and experimentation in neu- Neurology is the study of mankind itself, said rological patients, formulating hypotheses about the Wilder Penfield (1891–1976; Canadian neurosurgeon). neural correlates of consciousness and employing an You are your brain. This book offers neurological facts objective and reproducible methodology. This sci- on consciousness and impaired consciousness. While entific method, as first proposed by Isaac Newton philosophers have pondered upon the mind–brain (1643–1727; English polymath), has proven utterly conundrum for millennia, without making much if successful in replacing dark-age, ‘ magical thinking ’ any progress, scientists have only recently been able to with an intelligent, rational understanding of nature. explore the connection analytically through measure- Scientific methodology, however, also requires imagi- ments and perturbations of the brain’s activity. This nation and creativity. For example, methodologically ability again stems from recent advances in technology well-described experiments permitted Louis Pasteur and especially from emerging functional neuroimag- (1822–1895; French chemist and microbiologist) to ing modalities. As demonstrated in the chapters of this reject the millennia-old Aristotelian (384–322 BC; book, the mapping of conscious perception and cogni- Greek philosopher) view that living organisms could tion in health (e.g., conscious waking, sleep, dreaming, spontaneously arise from non-living matter. Pasteur’s sleepwalking and anaesthesia) and in disease (e.g., observations and genius gave rise to germ theory of coma, near-death, vegetative state, seizures, split- medical disease which would lead to the use of anti- brains, neglect, amnesia, dementia, etc.) is providing septics and antibiotics, saving innumerable lives. exiting new insights into the functional neuroanatomy The progress of science also largely depends upon of human consciousness. Philosophers might argue the invention and improvement of technology and that the subjective aspect of the mind will never be instruments. For example, the big breakthroughs of sufficiently accounted for by the objective methods of Galileo Galilei (1564–1642; Tuscan astronomer) were reductionistic science. We here prefer a more pragmatic made possible thanks to eyeglass makers’ improve- approach and see no reason that scientific and techno- ments in lens-grinding techniques, which permitted logical advances will not ultimately lead to an under- the construction of his telescopes. Similarly, advances standing of the neural substrate of consciousness. ix