Tuesday, April 13, 2010

Pharmacology and consciousness

Abstracts from the 9th Annual International Bioethics Forum that will take place April 22-23 2010 in Madison, Wisconsin.

Neurochemistry and Receptors as Mediators of Consciousness
David Nichols, Ph.D.
In the science of pharmacology, if one wishes to understand some physiological process, one can administer a substance that perturbs the process in some way, and then observe some effect that hopefully leads to understanding of the normal unperturbed process. Likewise, if one wishes to understand consciousness, the same principle should apply, and one could employ a substance that perturbs consciousness. As we know, psychedelics produce dramatic alterations in consciousness and would therefore seem to be perfect tools to help understand consciousness. Thus, this presentation will focus on some of the molecular aspects of psychedelics, including their brain targets, how they interact with those targets, the kinds of signals they generate, and some of the brain areas where these effects occur. There is now a general consensus that psychedelics activate the 5-HT2A type of serotonin receptor. These receptors are quite ancient, probably differentiating from the larger serotonin receptor family about 600-700 million years ago. Thus, these receptors have been around since the evolution of nervous systems began and, one might argue, have therefore been integrated into brain function at a very fundamental level. Reductionist neuroscience approaches to the study of this receptor in the brain will no doubt ultimately elucidate many of the components and processes involved in consciousness; the so-called “easy problems” of consciousness. It seems unlikely, however, that this knowledge will lead in any direct way to understanding consciousness. The explanatory gap between physical processes and consciousness is not one that will be easily bridged, but understanding how some of the component processes are affected by psychedelics may at least give some appreciation for the difficulty of the problem.

Psychological dimensions, neural networks and neurotransmitter dynamics associated with psychedelic-induced altered states of consciousness in humans
Franz X. Vollenweider, M.D. will first present new data on the phenomenology and structure of psychedelic-induced altered states of consciousness (ASC) based on a meta-analysis of a series of controlled studies conducted in healthy human subjects (n= 534) using state-of-the art psychometric and neuropsychological measures. Second, he will demonstrate that specific etiology-independent key dimensions of ASC, such as the experience of unity, ecstatic or anxious loss of ego-boundaries, religious exaltation or visionary states, are associated with circumscribed changes in brain activity in various extended neural networks. Third, he will also present novel data indicating that the serotonin 5-HT2A receptor together with the glutamate system plays a key role in the mechanism of action of classic hallucinogens such as psilocybin, and will discuss the implication of this recent finding for the understanding and putative treatment of some psychiatric disorders.
Geyer M. A. and Vollenweider F. X. (2008) Serotonin research: contributions to understanding psychoses. Trends Pharmacol. Sci. 29, 445-453.

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