Amphetamine-induced excitations predominate in single neostriatal neurons showing motor-related activity

Neostriatal single-unit activity was recorded in freely moving rats. A majority (62%) of the 24 recorded neurons were activated during motor behavior such as locomotion ( n = 11) or head movements ( n = 4). The behavioral response to amphetamine (1.0 mg/kg) was associated with increases ( n = 17) or decreases ( n = 7) in firing rate. A significantly greater proportion of motor-related neurons were excited by the drug compared to nonmotor-related cells. These results, which confirm the heterogeneity of amphetamine-induced effects in the neostriatum, indicate that the baseline motor-response characteristics of neostriatal neurons may determine their response to amphetamine.