The Development of a Match to Sample Memory Task and Test of Impulsivity to Investigate Rat Models of Schizophrenia

Abstract

Animal models of schizophrenia have been developed using chronic exposure to the dissociative anesthetics phencycladine (PCP) and ketamine to induce psychosis in rats. Preliminary research in our laboratory has shown marginal effects of low doses of PCP on the rat P300 event related potential (ERP) similar to those found in human male schizophrenics. As part of a broader program of research investigating the P300 ERP in a rat model of schizophrenia, we have been developing a battery of behavioral paradigms to test for memory deficits and impulsiveness that can be used to differentiate schizophrenic-like behavior from normal behavior in rats. The present research is directed toward developing a Y-maze match to sample (MTS) and a two lever MTS paradigm to screen for memory deficits. In these tests the rat receives a water reinforcer only if it chooses to run to the alley that was lighted or press the lever that was lighted during the sample phase. Memory is tested by inserting a delay interval during which the light cue disappears and the response is prevented. We are also developing a test of impulsivity in which the rat must inhibit a nose poke response until the third brief presentation of a light to obtain a water reinforcer. Early nose pokes result in a time out. Olin Hall construction delayed the initiation of this experiment. Accordingly preliminary results will be presented.