Gender differences in functional connectivity of left-handers during the passage of an emotional stroop task

Abstract

ntroduction. Neural correlates underlying the processing of emotional information, influence of emotional interference on cognitive control, gender difference in such activities remain a topic of research and discussion.Purpose. To study the connectivity of the brain regions involved in the processing of emotional information in left-handers, based on the EEG data obtained during their passage the emotional Stroop test (EST).Methods. EEG was registered during subjectpassage the EST successively two times. In EST a series including 240 words were presented at the center of the computer screen in one of two colors: red or green, words were emotional (negative) or neutral, shown in pseudorandom order. Some of these stimuli (target words names of animals and plants) participants were instructed to ignore (do not press any keys). Subjects were asked to respond with right hand (pressing P on a keyboard) for words printed in red and with left hand (pressing Q on a keyboard) for words printed in green. It was investigated source level functional connectivity (FC) in two groups of left-handers (17 to 22 years old): women (n=10) and men (n=10). FC was analysed between 21 regions of interest (ROI), selected on the base of fMRI research literature. Connections between ROIs were assessed using lagged phase synchronization (LPS) with eLORETA complex.Results. Statistically significant differences in FC by LPS between men and women groups were found only in first passage of EST. Particularly, FCof women, compared to men was: -higher between anterior cingulate cortex and left middle temporal area in delta band;-lower between left hippocampal formation and right frontal eye fields in beta-1;-and higher in beta-2 between right frontal eye fields and right anterior insula.were shorter for both emotional and neutral words. The interference effect was observed in both tests in women and only in the first test in men. Interference effect also was higher for responses with left hand for both groups. Repeated passage of the emotional Stroop test leads to reducing the effect of interference in men but not in women.Originality.The main neural networks have been identified, which in left-handed women are more involved in the processing of negative emotional information than in left-handed men.Conclusion. Compared to men, women have stronger connections of two areas of the brain involved in processing negatively colored emotional information, with other areas of the brain. The anterior cingulate cortex, which is considered to playan important role in attention and executive functions, is connected to the left middle temporal area, involved in the analysis of visual movement and words processing. Activation of theright anterior insular cortex, which is closely related to emotionalprocessing, is connected to the right frontal eye fields, which are known to play a key role in the goal directed eyes movements.Contrary, area of right frontal eye fields of men is more tightly connected to the contralateral left hippocampus, and is involved in semantic rather than emotional processing of information.Key words: emotional Stroop test;gender differences; left-handers; EEG; functional connectivity