Lesions of the dorsolateral striatum impair the acquisition of a simplified stimulus-response dependent conditional discrimination task

The dorsal striatum has long been thought to be important for some types of learning and memory, especially stimulus-response learning. Recently, we demonstrated that selective lesions of the dorsolateral striatum, but not dorsomedial striatum in rats, retarded the acquisition of two instrumental discrimination tasks thought to require stimulus-response learning. However, since these studies investigated the effects of dorsal striatal lesions on task acquisition, which can be confounded by differences in level of reinforcement and motor impairment caused by the lesion, the interpretation of these findings was somewhat problematic. The present experiment was designed to address these issues by assessing the effects of lesions of the dorsolateral striatum on a simplified version of the conditional discrimination task, in which the importance of reinforcement and motor factors was minimized. Animals with lesions of the dorsolateral striatum showed marked impairments in learning this task, a finding that is in agreement with the notion that the dorsolateral striatum is necessary for stimulus-response learning.