Acute effects of LSD on rhesus monkey operant test battery performance.

The acute effects of LSD were assessed in rhesus macaques using behavior in several complex tasks designed to model aspects of time estimation, short-term memory and attention, motivation, learning, and color and position discrimination. The end points monitored included percent task completed, response rate, and accuracy. LSD (0.0003-0.03 mg/kg intravenously) significantly decreased percent task completed and accuracy in the time estimation task at doses < or = 0.003 mg/kg, but did not significantly affect response rate in this task at any dose tested. Accuracy in the short-term memory task was significantly decreased at the highest dose tested (0.03 mg/kg), but no other end points were affected in this task. Response rate was decreased in both the motivation and learning tasks at doses (0.01 and 0.003 mg/kg, respectively) lower than those affecting other end points. In the color and position discrimination task, only response rate was affected (0.01 and 0.03 mg/kg). These data demonstrate that in rhesus monkeys, performance of tasks believed to depend on aspects of time estimation and motivation are more sensitive to the acute disruptive effects of LSD than are tasks thought to model learning, short-term memory, and color and position discrimination.