Effects of amphetamine, morphine, and CP 55, 940 on Go/No-Go task performance in rhesus monkeys

In humans, impulsivity measured as false alarms in a Go/No-Go task is reportedly decreased by amphetamine and is not affected by oxycodone and delta(9)-tetrahydrocannabinol. To model these findings in animals, three rhesus monkeys were trained to perform a food-reinforced Go/No-Go task. In this task, amphetamine was found to decrease false alarms (i.e. responding during No-Go trials), but only at doses that also decreased hits (i.e. responding during Go trials). Morphine generally decreased hits but not false alarms. The cannabinoid receptor agonist CP 55, 940 decreased both false alarms and hits, but only at doses that also decreased the number of trials completed. Additional studies in animals and humans are necessary to delineate the conditions under which amphetamine and other psychoactive drugs affect impulsivity in Go/No-Go tasks.