The neurophysiological basis of behavior and psychiatric disorders is for the most part unknown. However, over the years dysfunction of the dopaminergic system and, specifically, the basal ganglia have been implicated in many complex behaviors and psychiatric disorders. Evidence is presented in support of a basal ganglia role in sensory gating in the CNS and suggests a possible mechanism by which basal ganglia dysfunction may result in complex behavioral disturbances. Using schizophrenia as an example, this paper suggests that such disorders may to a certain extent represent a complex dysfunction of sensory filtering mechanisms in the brain. The suggestion is that the basal ganglia, acting as an active sensory information gating station, maintain the normal flow of afferent information to both ascending and descending structures. When this gating system is dysfunctional, unmodulated afferent information leads to inappropriate behavioral responses.