How Does Your Formulation of Lesion-Induced States of Diminished Consciousness Fit with AIM? Do You Suppose That Brain Stem Damage Affects Activation (A) and Modulation (M)?

Abstract

Comments on an article, Consciousness by J. Allan Hobson (1998). Allan Hobson's AIM model (Hobson 1998) is built according to three main dimensions. The first component, Activation, describes the brain's activation processes and is closely linked to the level of consciousness. According to the model, the brain is highly active in wakefulness and REM sleep but will show much less activity during NREM sleep. The second component, Input/output gateway, controls the inhibition of external stimuli. When slowly falling asleep, the gateway shuts down and inhibits the external stimuli; the brain is no longer involved in processing external perceptions. Then the brain starts its oniric phase and the focus switches to internal inputs. Finally, the third dimension, Modulation, refers to the different ways of cognitive processing (executive functions), judgment, volition and memory. According to the model, those cognitive processes are lacking in REM sleep because of the changes between the aminergic system and the cholinergic system. These three dimensions maintain a dynamic and reciprocal interaction over the sleep-wake cycle's variations (wakefulness, NREM, and REM sleep) and each of them can be expressed with lower or higher intensities depending on the level of consciousness. (PsycINFO Database Record (c) 2015 APA, all rights reserved)(chapter)