Frontal and Parietal Activities Associated With Different Inhibitory Processes in a Stroop-Matching/Stop-Signal Task: A Channel-Wise fNIRS Study.

Inhibition is an important component of cognitive control that encompasses multiple processes, such as interference control, inhibition of prepotent responses and suppression of ongoing responses. Frontal and temporoparietal regions of the cortex are implicated differently in inhibitory functions. The Stroop-matching/stop-signal task is a recent task that uses Stroop stimuli and stop-signals to create conditions that allow the investigation of the three forms of inhibition aforementioned. The task provides a way to distinguish the effect of these inhibitions as well as their interactions using a single task. The present study used functional near-infrared spectroscopy (fNIRS) to assess frontal and temporoparietal activations during the Stroop-matching/stop-signal task. The main objective was to investigate which cortical regions each inhibitory function would recruit during this task. Fifty-two young adults (mean age = 21.4, SD = 3.44) participated. Performance results indicated the effects previously found in the Stroop-matching/stop-signal task. fNIRS results showed that the left inferior frontal cortex (IFC) and the bilateral intraparietal sulcus are involved in interference control; the left IFC also showed activation in inhibition of prepotent responses; and the right IFC was involved in the suppression of ongoing responses. The interaction between suppression of responses and the other two forms of inhibition lead to deactivation of frontal and parietal areas. Thus, each form of inhibition demanded by the Stroop-matching/stop-signal task seems to recruit specific cortical regions, supporting the distinction between inhibitory components at the neurophysiological level.