Uncovering the links between physical activity and prosocial behaviour: A functional near-infrared spectroscopy hyperscanning study on brain connectivity and synchrony

The prevalence of sedentary lifestyles in modern society raises concerns about their potential association with poor brain health, particularly in the lateral prefrontal cortex (LPFC), which is crucial for human prosocial behaviour. Here, we show the relationship between physical activity and prosocial behaviour, focusing on potential neural markers, including intra-brain functional connectivity and inter-brain synchrony in the LPFC. Forty participants, each paired with a stranger, underwent evaluation of neural activity in the LPFC using functional near-infrared spectroscopy hyperscanning during eye-to-eye contact and an economic game. Results showed that individuals with exercise habits and more leisure-time physical activity demonstrated greater reciprocity, less trust, longer decision-making time, and stronger intra-brain connectivity in the dorsal LPFC and inter-brain synchrony in the ventral LPFC. Our findings suggest that a sedentary lifestyle may alter human prosocial behaviour by impairing adaptable prosocial decision-making in response to social factors through altered intra-brain functional connectivity and inter-brain synchrony.