Effects of anterior cingulate fissurization on cognitive control during stroop interference.

The midcingulate cortex, as part of the more anteriorly located cingulate regions, is thought to play a major role in cognitive processes like conflict monitoring or response selection. Regarding midcingulate fissurization, the occurrence of a second or paracingulate sulcus is more common in the left than in the right hemisphere and has been shown to be associated with an advantageous performance on tests of executive functions. However, the cognitive mechanisms underlying such behavioral differences are completely unknown. The current study addressed this issue by comparing subjects with a low and a high degree of left hemispheric midcingulate fissurization while collecting behavioral as well as electrophysiological correlates of Stroop interference. A high degree of fissurization was associated with decreased behavioral Stroop interference accompanied by a stronger and prolonged frontal negative potential to incongruent trials starting around 320 ms. This increased frontal negativity is assumed to reflect an enhanced activity of a conflict monitoring system located in the midcingulate cortex. In contrast and starting around 400 ms, subjects with low fissurization revealed an increased positivity over parieto-occipital regions suggesting a compensatory need for enhanced effortful cognitive control in this group. These results contribute to the understanding of the neuronal implementation of individual differences regarding attentional mechanisms.