Primate information processing under sodium pentobarbital and chlorpromazine: differential drug effects with tachistoscopically presented discriminative stimuli.

Sodium pentobarbital and chlorpromazine were evaluated for the degree to which they differentially reduce the speed or efficiency with which sensory information can be processed. Rhesus monkeys were tested under comparable doses of sodium pentobarbital and CPZ on a visual discrimination problem with varying durations of tachistoscopically presented stimulus information. When unlimited stimulus information was available, no effects of the two drugs were observed at the doses used, but as the duration of stimulus presentation was progressively decreased, the effects of sodium pentobarbital became more severe, whereas CPZ did not differe from the saline control an any presentation duration. While previously published literature indicates that CPZ impairs performance by intermittantly blocking sensory input or transmission, the present data provide the first direct behavioral confirmation that barbiturates impair performance by retarding the rate at which sensory stimuli can be processed and utilized.