1 — A model of affective disorders is presented based on two antagonizing subsystems in the CNS: the reward system (or euphoria system) and the punishment system (or dysphoria system), the former consisting of the septal area and medial forebrain bundle and parts of the limbic system, the Jatter consisting of the periventricular system and also parts of the limbic system.
Various psychogenic and organic factors affecting mood are discussed and laboratory findings are reviewed which make it probable that the reward and punishment system indeed play a mediating role in the effect of these factors.
II — The model is used to gain insight, on a physiological level, in depressive symptoms like anhedonia and apathy. Links are suggested between the model and what is known about the biochemical aspects of affective disorders. The factors leading to depression are categorized in genetic, past and present factors and an attempt is made to understand how they impair the balance between the euphoria and the dysphoria system. The possibility is shown to base the classification of ffective disorders on a better understanding of the central processes regulating mood.