Acute effects of methylenedioxymethamphetamine (MDMA) on several complex brain functions in monkeys.

The effects of MDMA were assessed in rhesus macaques using behavior in an operant test battery (OTB) consisting of five food-reinforced tasks designed to model aspects of time estimation, short-term memory, and attention, motivation, learning, and color and position discrimination. Testing occurred 30 min after intramuscular, injections of MDMA (0.0, 0.1, 0.3, and 1.0 mg/kg). The behavioral endpoints monitored included percent task completed, response rate or latency, and response accuracy. Percent task completed was significantly decreased in the time estimation, learning, and motivation tasks at 1.0 mg/kg as compared to saline controls. Response accuracies in the time estimation and learning tasks were also decreased at 1.0 mg/kg. Response rate was decreased at 1.0 mg/kg in the motivation task but was not significantly affected in any other tasks. No behavioral endpoints were significantly affected in the short-term memory and attention and color and position discrimination tasks at any dose tested. Results indicate that time estimation, motivation, and learning are more sensitive to the acute effects of MDMA than are short-term memory and attention and color and position discrimination.