Individuals with mild stress levels had higher sensitivity to the social tactile stroking: an fMRI study

Mild levels of stress may lead to compensatory changes in perceptual strategies, especially during social affective stroking. We recruited 17 healthy adults with moderate levels of psychological stress, as assessed by the PSM-25 questionnaire and clinical interviews, and 17 participants with low levels of stress. Tactile stimulation involved slow gentle stroking by the researcher's hand of two areas: the foot and the shin. We analyzed the regions of interest signal by examining all activated clusters in 34 participants and also analyzed group-specific BOLD signals. Our findings suggest an increased sensitivity to social tactile stroking in stressed individuals, which correlated with increased activity in areas related to tactile perception, including the left parietal and central operculum, as well as the left precentral gyrus. Additionally, we observed activation in brain regions involved in inhibitory control and theory of mind, such as the left caudate nucleus, left middle cingulate cortex, left anterior insula, and left superior temporal gyrus. Sex differences were also noted: compared to women, men showed higher activation in the middle occipital gyrus, superior parietal lobe and left middle frontal gyrus. This study sets the stage for future research into perceptual strategies and their biochemical correlates in highly stressed or distressed participants.