Does the brain have a center of consciousness? Until now, the prevailing opinion has been that anesthetics and other agents of unconsciousness act widely across the cerebral cortex and spinal cord. But a new finding suggests the existence of a barbiturate-sensitive switch (M. Devor, et al., "Reversible analgesia, atonia, and loss of consciousness on bilateral intracerebral microinjection of pentobarbital," Pain, 94:101-12, October 2001). Using barbiturate microinjections, Hebrew University of Jerusalem researchers surveyed most of the subcortical forebrain, midbrain, and hindbrain of rats. An anesthesia-like state was induced when the drugs were administered to a small, football-shaped area in the upper brainstem's reticular formation that they dubbed the mesopontine tegmentum anesthesia locus (MPTA). "I'm not sure that the MPTA can be represented as a 'center' of consciousness in the sense that its neurons run an algorithm that manifests awareness," warns biology professor and coauthor Marshall Devor. "I prefer to...
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