A growing number of studies have investigated how motivation interacts with particular cognitive functions, including attention, working memory, and other executive functions. In these studies, the emphasis has been on understanding how motivation impacts brain regions that contribute to improving behavioral performance. Less is understood about how positive incentives may actually impair behavioral performance. Here, we were interested in investigating a situation in which reward would be potentially deleterious to behavioral performance. Specifically, we hypothesized that rewarding participants for correct going would impair stopping performance. Critically, we hypothesized that the effects on inhibition would be specific, namely, not simply attributable to a speeding-up of reaction time during go trials. To investigate the interaction between inhibition and motivation, participants performed a stop-signal task during two conditions, namely, during a neutral, control condition and during a rewarded condition during which they were rewarded for correct go performance. Behaviorally, participants exhibited longer stop-signal reaction times during the reward relative to the control condition, indicating that it was harder to inhibit their responses during the former condition. Neuroimaging findings revealed that a host of brain regions were involved in stop-signal inhibition, as indexed via the contrast of successful and unsuccessful stop trials. Critically, a subset of these regions, which included the right inferior frontal gyrus, the left precentral gyrus, and bilateral putamen, exhibited significant inhibition by condition interactions, demonstrating that cognitive and motivational signals interact in the brain during inhibitory control.
2009 Elsevier Ltd. All rights reserved.