The dissociation of neural circuits in a Stroop task.

The Stroop effect refers to an increase in response time observed when the word meaning and the stimulus hue do not match. In an incongruent condition, the word 'green' is presented in the color red, whereas in a congruent condition the word 'red' is presented in the color red. To determine at what level of processing the Stroop effect takes place, we recorded event-related potentials while participants engaged in a modified Stroop task. The results revealed that the incongruent condition elicited more negative event-related potential deflections, N300 and N520, than the congruent condition, which provide evidence for the dissociation of neural circuits between detection interference and response inhibition in a Stroop task. Dipole analysis of the difference wave (incongruent-congruent) localized the generator of the N300 to the posterior cingulate cortex, which might be related to the inhibition of the unrelated interference attribute in the early phase of cognitive processing.