Lesions of the medial and lateral striatum in the rat produce differentialdeficits in attentional performance

Excitotoxic lesions of the medial frontal cortex and anterior cingulate cor tex in rats have been shown to produce dissociable impairments on a reactio n time visual attention (5-choice) task. Because these cortical areas proje ct to the medial striatal region, the authors predicted similar deficits af ter lesions of this striatal area compared with the lateral area. Compared with sham-operated controls, rats with quinolinic acid-induced medial stria tal lesions showed all the behavioral changes associated with medial fronta l cortex and anterior cingulate cortex lesions. In contrast, lateral striat al lesions produced profound disturbances in the performance of the task. C ontrol tests showed little evidence of gross deficits in either group of ra ts in terms of motivation, locomotor function, or Pavlovian appetitive cond itioning. These data suggest that the medial and lateral striatum have cont rasting roles in the control of instrumental responding related to the prim ary sources of their cortical innervation.