Moment-to-moment fluctuations in fMRI amplitude and interregion coupling are predictive of inhibitory performance.

We investigated how moment-to-moment fluctuations in fMRI amplitude and interregional coupling are linked to behavioral performance during a stop signal task. To quantify the relationship between single-trial amplitude and behavior on a trial-by-trial basis, we modeled the probability of successful inhibition as a function of response amplitude via logistic regression analysis. At the group level, significant logistic slopes were observed in, among other regions, the inferior frontal gyrus (IFG), caudate, and putamen, all bilaterally. Furthermore, we investigated how trial-by-trial fluctuations in responses in attentional regions covaried with fluctuations in inhibition-related regions. The coupling between several frontoparietal attentional regions and the right IFG increased during successful versus unsuccessful performance, suggesting that efficacious network interactions are important in determining behavioral outcome during the stop signal task. In particular, the link between responses in the right IFG and behavior were moderated by moment-to-moment fluctuations in evoked responses in the left intraparietal sulcus. A supplemental figure for this article may be downloaded from http://cabn.psychonomic-journals.org/content/supplemental.