Brain Activity Related to the Congruent and Incongruent Part of the Stroop Test Performance- Not Only Differences but Also Similarities in the Brain Activity Pattern. a Neuroimaging Pet(h2o15) Study

Previous studies on brain activity during the completion of the Stroop test focused mainly on finding differences between brain activity during the completion of the congruent and incongruent parts of the test. Based on the results of those studies, the key role of the DLPFC and the ACC was emphasized in solving the cognitive conflict accompanying the completion of the incongruent part of the Stroop task. Less attention was paid to other areas of the brain that form a neurofunctional system involved in the Stroop task. The aim of the study was to examine brain activity during the completion of the non-interferential and interferential parts of the Stroop test. Colour-word congruent (A), incongruent (B), and baseline (C) conditions were presented in two ABC trials to 18 healthy, right-handed study participants during 8 H2O15 PET scans. SPM8 (Statistical Parametric Mapping – http://www.fil.ion.ucl.ac.uk/spm/) was used for a voxel-by-voxel analysis of the neuroimaging data. Both A and B task performances are related to increased activity in the area of the frontal lobes (the inferior frontal gyrus on both sides and the right dorsolateral prefrontal cortex), areas of the medial prefrontal cortex (including the cingulate gyrus), some areas of the occipital lobes, and the temporal lobes, including the insula. We can also observe some subcortical activation of thalamic and cerebellar structures. A similar activity pattern for most brain areas occurs during the noninterferential and interferential parts of the Stroop test. In addition to the prefrontal areas, which have so far been of the greatest interest for researchers in terms of their significance in solving a cognitive conflict, other cortical and subcortical areas are involved in the completion of the Stroop test. Therefore, it can be concluded that structural damage to or dysfunction of any of them affects performance in the Stroop test.