Acquisition, but not retrieval of delayed alternation is impaired by ketamine

Dissociative anaesthetics as ketamine and related drugs induce marked behavioral changes in rats, in particular behavioral stereotypies and learning impairments. In the present study the effect of ketamine on acquisition and retrieval of a delayed alternation task was investigated. Results indicate that ketamine (8mg/kg i.p.) impaired specifically acquisition, while retrieval was not affected. Thus, stereotypies competing with ongoing behavior and therefore interfere with learning, appear not to be causative to the acquisition deficit, since retrieval should be affected in the same way. A possible involvement of NMDA receptors in deficient acquisition is discussed.