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

The effects of phencyclidine (PCP; a noncompetitive NMDA antagonist) were assessed in rhesus monkeys using performance in an operant test battery (OTB) consisting of five food-reinforced tasks thought to engender responses dependent upon aspects of time estimation, short-term memory, 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 of PCP (0.00, 0.003, 0.01, 0.03, 0.1, 0.13, 0.18, and 0.3 mg/kg). PCP disrupted performance of all tasks at 0.30 mg/kg. PTC was significantly decreased in the time estimation, motivation, and learning tasks at doses greater than or equal to 0.13 mg/kg. PTC for the short-term memory and color and position discrimination tasks was significantly decreased 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 color and position discrimination tasks. Response accuracy was significantly 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 discrimination task being the least sensitive. These results are different than those obtained from earlier studies on the effects of MK-801, a more selective noncompetitive NMDA antagonist.