Effect of haloperidol and chlorpromazine on reversal learning of normal and striatectomized rats in a Y-maze.

Haloperidol (0.05-0.1 mg/kg) and chlorpromazine (0.5-1.0 mg/kg) improved reversal learning avoidance responses in a Y-maze, decreased intersessional fluctuations of errors and decreased the number of spontaneous exits from a correctly selected chamber. After bilateral lesions of the striatum this effect disappeared. Brain lesions also attenuated the ability of neuroleptics to suppress amphetamine-induced stereotypy and and accompanying defects in avoidance responses. The improvement of avoidance behavior by neuroleptics may be related to the reduction of spatial preference caused by functional asymmetry between the bilateral nigro-striatal systems.