Chunk #18 — 1 Definitions and Conceptual Framework for Reward Deficit in Alcoholism — 1.1 Theoretical Framework: Motivation, Withdrawal, and Opponent Process
Animal models can also be used to test the hypothesis that there are opponent process-like motivational changes associated with the development of alcohol dependence. Electrical brain stimulation reward or intracranial self-stimulation has a long history as a measure of activity of the brain reward system and of the acute reinforcing effects of drugs of abuse. All drugs of abuse, when administered acutely, decrease brain stimulation reward thresholds (Kornetsky and Esposito 1979) and when administered chronically increase reward thresholds during withdrawal (see above). Brain stimulation reward involves widespread neurocircuitry in the brain, but the most sensitive sites defined by the lowest thresholds involve the trajectory of the medial forebrain bundle that connects the ventral tegmental area with the basal forebrain (Olds and Milner 1954; Koob et al. 1977). Although much emphasis was focussed initially on the role of the ascending monoamine systems in the medial forebrain bundle in brain stimulation reward, other nondopaminergic systems in the medial forebrain bundle clearly play a key role (Hernandez et al. 2006).
