Phencyclidine disturbs relational memory in the transitive inference task.

ABSTRACT

Transitive inference, that is, the ability to infer relationships among stimuli that are only indirectly associated, is impaired in schizophrenic patients and in rats with lesions of the prefrontal cortex. Symptoms of schizophrenia can be pharmacologically modeled by administration of the N-methyl-D-aspartate receptor antagonist, phencyclidine (PCP). Here, a subchronic administration of PCP (2.5 mg/kg for 5 days) to well-trained rats impaired the subsequent transitive inference judgment; the effect was observed 3 days, but not 10 days after the last dose. These results support the findings showing that PCP administration impairs cognitive domains specifically affected in schizophrenia in addition to mimicking the 'positive' and 'negative' symptoms of the disorder.