The stuff that dreams are made of

The Dream Drugstore: Chemically Altered States of Consciousnessby J. Allan Hobson, MIT Press, 2001. US$ 27.95 /£19.50 (360 pages) ISBN 0 2620 8293 4Consciousness as a neuroscientific concept incorporates several different states of cerebral function. The term is often applied to different states of responsiveness to the environment – being conscious or in a coma, awake or asleep. In The Dream Drugstore, J. Allan Hobson offers a new understanding of altered states of consciousness based on knowledge of how our brain chemistry is balanced when we are awake and how that balance changes when we sleep and dream. There are no a priori rules governing the relationship between conscious mental events and brain events; the rules are only now being discovered. The neuronal basis of our subjective experiences forms the basis of the problem of the mind–brain relationship. Are there unique neuromodulatory chemical systems for conscious experience that change when we dream? To answer this fundamental question, Hobson develops a three-way analogy between dreaming, psychosis and psychedelic experience. The aim of this work is to provide a conceptual framework to understand mind, brain and drug action that is based on circuit-level neuroanatomy and physiology. In this format, Hobson attempts to explain a variety of brain-based experiences, covering the gamut from lucid dreaming, sleep and dream disorders to religious experience, hallucinations, psychosis and good and bad psychedelic trips.This is a well-written and information-packed read on a topic that represents the culmination of Hobson's lifetime of scientific work in the areas of dream process and dream theory. This new book fills a big gap in the field of dream research and Hobson is to be commended for going far beyond the usual account of human sleep physiology and the association of dreaming with REM sleep. The psychological features of dreaming in humans, and identification of the occurrence of this physiological state in all mammals, set the stage for correlating the mental state of dreaming with Hobson's psychophysiological-systems model. This model includes internal brain activation throughout a REM episode together with blockade of input from the outside world. As a result of disinhibition caused by cessation of aminergic neuronal firing, brain-stem reticular neurons autoactivate. The brain that lacks afferents and is internally activated quells motor outputs to prevent disruption of sleep by dreamed motor commands. The dream-activated, but disconnected, brain floods with internal signals that are processed as if they came from the outside world. And this is Hobson's view of the neurobiological stuff that dreams are made of.This six-part, 16-chapter work is written in the style of a personal monograph with much historical reference, including (but not limited to) the imaginative dream theory of Sigmund Freud, some of Jean Martin Charcot's neurological vignettes and Aldous Huxley's philosophy and mysticism. It tells a story that starts in section I by defining states of consciousness and how they alter. It then goes on, in section II, to discuss the neurodynamics of mental states, including dreaming, dissociation and hypnosis. Section III covers normal and abnormal alterations of consciousness. This section includes an overview of the neurophysiology of REM and non-REM sleep and state-dependent models of amine- and ACh-mediated neuromodulation. In section IV, The Medical Drugstore, Hobson provides an interesting discussion of the psychopharmacology of anxiolytics, drugs for sleep, mood regulators and antipsychotics. In section V, The Recreational Drugstore, he deals with hallucinogens, opiates and cocaine, and their effects on mind-brain. The discussion of the phenomenology of hallucinogens, and the way in which they impose REM-like physiological conditions on waking (i.e. a ‘waking dream state’) was provocative. In section VI, The Psychological Drugstore, Hobson gives us his view of the treatment implications of altering the mind–brain without chemicals. The content of these sections shows the benefit of an experienced clinical psychiatrist with a critical and philosophical mind.This book should be read by clinical neuroscientists, researchers and students of neuroscience, even if sleep research is not their major subject. This book is an essential read for anyone interested in the chemistry of consciousness.