[Sex Differences in Visual Task Switching (an fMRI Study)]

Executive functions are an important ability of human brain to program, regulate and control various cognitive processes; one of these processes is the voluntary task switching. However, the sex differences in this process are poorly studied. In our study, these differences were investigated in 70 healthy subjects (36 men and 34 women) aged 21-48 years by means of functional magnetic resonance imaging (fMRI) and neuropsychological examination. During the fM RI study, the subjects had to shift their attention between two tasks (classifying figures according to their form or number). During neuropsychological examination, the subjects completed a series of visual attention, task switching and memory tests. The results of fMRI study showed that visual task switching in women is carried out by a neuronal network, consisting of dorsolateral prefrontal cortex, inferior parietal areas, secondary visual areas of both hemispheres and cerebellum cortex. Task switching in men involved the same areas and, in addition, right supplementary motor area, right insula and left thalamus. As compared with women, the rate of activation of prefrontal cortex, left parietal lobe and right insula in men was significantly higher. The results of neuropsychological tests showed that men completed the tasks with attention switching, searching and arranging of stimuli significantly slower than women. The data demonstrate the differences in the organization of task switching processes in men and women.