The latent inhibition model dissociates between clozapine, haloperidol, and ritanserin

Latent inhibition (LI), i.e., retarded conditioning to a stimulus following its nonreinforced preexposure, is impaired in some subsets of schizophreni a patients and in amphetamine-treated mts. Typical and atypical antipsychot ic drugs (APD's) potentiate LI, but to date the model has not dissociated b etween them. This study demonstrates such a dissociation using haloperidol (0.1 mg/kg), clozapine (5 mg/kg), anti ritanserin (0.6 mg/kg) administered in preexposure and/or conditioning. Under conditions which did not yield LI in vehicle controls 140 preexposures and five conditioning trials), both h aloperidol and clozapine, but not ritanserin, led to LI when administered i n conditioning. Under conditions which led lo LI in vehicle controls (40 pr eexposures and two conditioning trials), clozapine and ritanserin, but not haloperidol, abolished LI when administered in preexposure. It is suggested that LI potentiation via conditioning detects Nle "typical" action of APDS whereas LI disruption via preexposure detects the "atypical" action of APD 's. (C) 2000 American College of Neuropsychopharmacology. Published by Else vier Science Inc. All rights reserved.