AIM model
a model proposing that various states of consciousness may be defined and differentiated according to their position on three axes of brain activity: (a) Activation—how active is the brain when one is awake, in NREM sleep, or in REM sleep, as measured by electroencephalography?; (b) Input–output gating—how is information that is processed by the brain during each phase in the sleep–wake cycle generated, via external sensory input (as in external stimuli during waking) or internally (as in dreams)?; and (c) Modulation—which neurochemical modulatory system is predominant during each phase, the aminergic or the cholinergic? The model has been used to investigate altered states of consciousness and various phenomena associated with dreaming (notably the lucid dream); it has also been proposed more generally as an approach to the mind–body problem. It was devised by U.S.
psychiatrist J. Allan Hobson (1933– ) as an expansion of the earlier activation–synthesis hypothesis that he developed with U.S. psychiatrist Robert W. McCarley (1937– ).