Marked behavioral and biochemical sensitivity to lesion size in the posterior cortex of the rat

Unilateral focal cortical suction lesions of varying diameter from 0.7 to 2.0 mm were made in the right posterior lateral cortex of rats. Only the 1.0 mm lesion size resulted in spontaneous postoperative hyperactivity. This increased activity was accompanied by significant elevations in substantia nigra and caudate nucleus dopamine concentrations. Other lesion sizes did not affect behavior or brain biochemical concentrations in this fashion. These results suggest a functional organization in this area of posterior cortex which affects both neurochemistry and behavior.