PubMed | U.S. National Institutes of Health and Center for Neuroscience and Regenerative Medicine Bethesda
Type: | Journal: Frontiers in human neuroscience | Year: 2015
Being able to stop (or inhibit) an action rapidly as in a stop-signal task (SST) is an essential human ability. Previous studies showed that when a pre-stimulus cue warned of the possible need to stop a response in an upcoming trial, participants response time (RT) increased if the subsequent trial required a go response (i.e., go RT cost) relative to a trial where this uncertainty was not present. This increase of the go RT correlated with more efficient response stopping. However, it remains a question whether foreknowledge of upcoming inhibition trials given prior to the task is sufficient to modulate neural activity associated with the primary go responses irrespective of whether stopping an overt response is required. We presented three task conditions with identical primary (i.e., go) response trials but without pre-stimulus cues. Participants were informed that Condition 1 had only go trials (All-go condition), Condition 2 required a stop response for some trials (Stop condition), and Condition 3 required a response incongruent with the primary response (i.e., Switch response) for some trials (Switch condition). Participants performed the tasks during functional magnetic resonance imaging (fMRI) scans. Results showed a significant increase in the go RT (cost) in the Stop and Switch conditions relative to the All-go condition. The go RT cost was correlated with decreased inhibition time. fMRI activation in the frontal-basal-ganglia regions during the go responses in the Stop and Switch conditions was also correlated with the efficiency of Stop and Switch responses. These results suggest that foreknowledge prior to the task is sufficient to influence neural activity associated with the primary response and modulate inhibition efficiency, irrespective of whether stopping an overt response is required.