What does consciousness have to do with psychiatry? It is certainly true that we diagnose, conduct a mental status exam, and complete a clinical interview, for example, only with patients who are conscious. While our understanding of consciousness is in its infancy and we have much to learn, it is doubtful that any clinician will ever be able to meaningfully provide a neuropsychiatric diagnosis of comatose or sleeping patients. We can imagine how new technologies, such as magnetoencephalography, or functional imaging while performing adaptive tasks, will enable us to observe some of the neural processes (though not the experienced mental contents) in states of dissociation, or mania, or even the excitement of an erotic dream. In each of these examples,
Textbook of Biological Psychiatry. Edited by Jaak Panksepp Copyright © 2004 by Wiley-Liss, Inc. ISBN: 0-471-43478-7
such technologies will be drawing the outlines of a working mind. The functional relationship and intimacy between the field of psychiatry and the state of consciousness in the patient has often been taken for granted, but this represents a serious neglect. Psychiatry on the whole has paid little attention to just what consciousness might be, particularly in terms of its neural substrates. Yet the notion of consciousness must be acknowledged as the very epicenter of any concept of mind, such that any deep understanding of the disordering of mind, behavior, and emotion central to psychiatric and neuropsychiatry syndromes mandates a deeper understanding of consciousness. From these considerations, there can be little doubt that psychiatry will need to pay increasing systematic attention to consciousness as a foundational process for future progress. If we unravel the neurobiological bases for consciousness, we may discover many new psychiatric treatments, potentially even highly effective therapies we currently could barely imagine.
In the current climate of an exponentially expanding neuroscience, one of the most compelling questions still without a definitive answer is "What is consciousness really made of?" The nature of consciousness, like the nature of emotion, is a topic as old as culture, and yet still in its neuroscientific infancy (the word conscious did not enter the English vocabulary until the 17th century as before that time it was referred to as conscience). As scientific topics, both emotion and consciousness have just recently emerged from a scientific dark age in which behaviorism informed a systematic and deliberate neglect of both phenomena. Under the sway of behaviorism, consciousness was viewed as either impossible to understand or simply not an appropriate subject for serious scientific study. While these old prejudices are still active in some quarters, they are no longer scientifically justified, particularly in view of the growing empirical literature on consciousness emerging in both neuroscience and cognitive science. There has been a major renaissance of scientific interest in consciousness and its neural substrates over the past 10 years, and science no longer sleeps under the blanket assumption that subjectivity itself should, or even could, be neatly removed from the scientific equation. However, one might still wonder why a chapter on the topic of consciousness is included in a textbook of biological psychiatry. Some of the more obvious reasons are as follows:
1. There are a number of fundamental syndromes in clinical neuroscience best conceptualized as primary diseases or disorders of consciousness [schizophrenia, coma, persistent vegetative state (PVS), akinetic mutism, and delirium as just five of the more prominent]. Although several of these (coma, PVS, and to a lesser extent akinetic mutism) have traditionally been seen as the province of neurology, both disciplines are moving toward synthesis, and these syndromes also potentially inform basic issues in psychiatry.
2. Many other clinical syndromes in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), including anxiety disorders, affective disorders, autism, posttraumatic stress disorder (PTSD), and borderline and other personality disorders are probably best conceptualized as fundamental disorders of affect and affective regulation. While many psychiatric clinicians and researchers tend to consider disorders of affect as distinct from disorders of consciousness, recent work suggests that affect and affective regulation may be foundational for "core" or primary consciousness, and therefore the understanding of affect and consciousness are deeply intertwined.
3. The monoamine systems [dopamine (DA), norepinephrine (NE), and serotonin or 5-hydroxytryptamine (5-HT)] and acetylcholine (ACh), almost exclusively the focus of classical clinical psychopharmacology, are key components of what is now conceptualized as an extended reticular activating system, comprising a multicomponent, distributed system for global state control foundational to consciousness. This suggests that most psychiatric therapies affect core aminergic components of these extended reticular activating systems (RAS) underpinning basic arousal mechanisms, and that the neural substrates of consciousness are more immediately relevant to psychiatry than generally appreciated.
For students relatively new to this topic, we would first acknowledge the intrinsic difficulty of the domains addressed in this chapter: (1) difficult philosophical issues about the ontological status of consciousness (what is it and how is it related to other phenomena); (2) terminological issues in the nosology of consciousness, including basic distinctions between a primary, core consciousness and its cognitive extensions ("extended consciousness"); (3) a new typology for diseases of consciousness and their complex lesion correlates; (4) a clinical case study section presenting two diseases of consciousness normally outside the domain of classical clinical psychiatry; (5) a complex and highly distributed neuroanatomy of consciousness; and (6) concepts from neurodynamic theory that attempt to explain how highly distributed neuronal systems might function in an integrated fashion to generate conscious states. Readers new to these subject matters may struggle with some of these concepts, but the three case studies provided should help anchor these complexities in the phenomenology and behavior of real clinical cases.
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