ACUTE BEHAVIORAL-EFFECTS OF PHENCYCLIDINE ON RHESUS-MONKEY PERFORMANCE IN AN OPERANT TEST BATTERY

The effects of phencyclidine (PCP; a noncompetitive NMDA antagonist) w ere assessed in rhesus monkeys using performance in an operant test ba ttery (OTB) consisting of five food-reinforced tasks thought to engend er responses dependent upon aspects of time estimation, short-term mem ory, motivation, learning, and color and position discrimination. End- points included percent task completed (PTC), response rate or latency , and response accuracy. Testing occurred 15 min after IV injections o f PCP (0.00, 0.003, 0.01, 0.03, 0.1, 0.13, 0.18, and 0.3 mg/kg). PCP d isrupted performance of all tasks at 0.30 mg/kg. PTC was significantly decreased in the time estimation, motivation, and learning tasks at d oses greater than or equal to 0.13 mg/kg. PTC for the short-term memor y and color and position discrimination tasks was significantly decrea sed at 0.18 mg/kg and above. Response rate was significantly decreased at 0.13 mg/kg and above in the motivation and learning tasks and at 0 .18 mg/kg and above in the time estimation, short-term memory, and col or and position discrimination tasks. Response accuracy was significan tly decreased in the time estimation, short-term memory, and learning tasks at doses greater than or equal to 0.13 mg/kg, while accuracy in the color and position discrimination task was decreased only at 0.30 mg/kg. PCP's effects on OTB performance were generally nonspecific, in that the time estimation, short-term memory, learning, and motivation tasks were all equally sensitive, with the color and position discrim ination task being the least sensitive. These results are different th an those obtained from earlier studies on the effects of MK-801, a mor e selective noncompetitive NMDA antagonist.