Behavioural topography in the striatum: differential effects of quinpirole and D-amphetamine microinjections

Behavioural evidence has accumulated that supports the hypothesis that specific territories of the striatum contribute differentially to the control of motor behaviours. The present experiments compare the behavioural effects of microinjections of amphetamine (20 microg/0.5 microl) with those elicited by the D2-class dopamine receptor agonist quinpirole (3 microg/0.5 microl) following direct microinjection into three anatomically distinct sectors of the striatum: the nucleus accumbens, the ventrolateral striatum and the anterodorsal striatum. Our findings demonstrate that site-specific behavioural responses are induced by microinjections of amphetamine, but not of quinpirole, into the striatum. Our results suggest that widespread areas of the striatum are implicated in the induction of a syndrome of sedation, yawning and motor inhibition, observed readily following microinjections of quinpirole into the striatum. This evidence supports both homogeneity and segregation of function in the striatum at the behavioural level. Further, the results suggest that the elicitation of site-specific action sequences at the level of the striatum seems to require cooperative interactions between D1-class and D2-class dopamine receptors.