Postreinforcement changes of steady potentials in premotor cortex of monkeys

Abstract

Slow potential changes were recorded from premotor cortex and several subcortical regions during a reaction time foreperiod experiment. When reinforced trials were alternated in blocks of 5 trials with unreinforced trials, the cortical DC potential increased in negativity to about −300 μV over the course of reinforced trials and declined to baseline during nonreinforced trials. Change in the cortical potential occurred after ingestion of liquid reinforcement was completed. Since positive potentials have been reported to appear in posterior cortex during reinforcement, the frontal potential was thought to be a frontally unique phenomenon and was referred to as postingestion frontal negativity (PIFN). No similar changes occurred in subcortical sites.