Cardiac sympathetic-parasympathetic activity and reactivity during mentalizing in healthy young adults

Mentalizing-the ability to understand and attribute mental states to others-relies on effective self-regulation and social-cognitive processing, both of which may be shaped by cardiac autonomic responses. While prior research has primarily emphasized the role of cardiac parasympathetic (PSNS) activity in social cognition, the contribution of cardiac sympathetic (SNS) activity and its dynamic interaction with PSNS remains underexplored. This study simultaneously investigated resting and task-related cardiac sympathetic-parasympathetic activity and reactivity to examine the associations with mentalizing performance in healthy young adults (N = 120). Resting heart rate variability and systolic time intervals were used to index cardiac PSNS and SNS activity, respectively, with phasic reactivity calculated as percentage change scores during mentalizing performance. Hierarchical regression analyses showed that higher cardiac PSNS activity and lower cardiac SNS activity at rest jointly predicted better mentalizing performance. Importantly, reduced cardiac SNS reactivity-but not cardiac PSNS reactivity-was a stronger predictor of mentalizing performance, and further mediated the relationship between resting cardiac autonomic activity and mentalizing performance. These findings highlighted the importance of cardiac SNS control, alongside cardiac PSNS control, in supporting socio-cognitive processing. This study suggested the understanding of efficient regulation to physiological arousal and advocated for an integrative cardiac psychophysiological model of social cognition that incorporates both cardiac sympathetic-parasympathetic branches.