Granger Causality Analyses for the Anterior Cingulate Cortex and Dorsolateral Prefrontal Cortex during Performance of the Simon Task.

Abbreviations: ACC, anterior cingulate cortex; BA, Brodmann area; DLPFC, dorsolateral prefrontal cortex.†Granger causality indices (mean±standard deviation) of functional connectivity between the ACC and DLPFC subregions, including BA46, 44, 8, and 45. The ACC seed region was an 8 mm-radius sphere centered at the voxel (x = −6, y = 28, z = 31) in which stuttering speakers activated more strongly relative to fluent speakers during conflict resolution. The DLPFC seed regions were defined using 8 mm spheres placed at the foci of activation (BA46, x = −48, y = 30, z = 16; BA44, x = −54, y = 12, z = 15; BA8, x = −46, y = 10, z = 40; BA45, x = −53, y = 23, z = 14) in which stuttering speakers showed blunted activation during context-dependent adaptation.††Between-group comparisons of Granger causality indices.