Effects of delta-9-tetrahydrocannabinol on temporal and auditory discrimination performances of monkeys.

Abstract

In two experiments, macaques were trained to respond differentially to either the duration of a visual stimulus or to the frequency of an auditory clicker. In the duration discrimination experiment, delta-9-tetrahydrocannabinol (delta-9-THC) was administered acutely in doses from 1 to 16 mg/kg, producing dose-related decrements in accuracy of the discrimination performance, and a reduction in the rate at which the animals initiated discrimination trials. In both the duration and auditory discrimination experiments, chronic daily administrations of 2 to 16 mg/kg of delta-9-THC produced an initial decrement in accuracy and rate of trial initiation. Both measures showed some development of tolerance, tending to return to baseline levels, however, the time course of tolerance was different for the measures, with the rate of trial initiation recovering more quickly than accuracy. No differences in response to the drug were attributable to the different modalities used in these two experiments.