Neural Control of Autonomic Arousal During Threat Anticipation Revealed by High-Resolution Cardiac Contractility.

The sympathetic nervous system prepares the organism for adaptive action by shaping physiological, affective, and behavioral responses to environmental demands. Yet, how sympathetic signals dynamically couple with neural systems supporting emotional experience and behavior remains poorly understood, in part because common indices such as skin conductance responses lack sufficient temporal resolution to track these dynamics. Here, we evaluated trans-radial electrical bioimpedance velocimetry (TREV), a non-invasive measure of beat-to-beat cardiac contractility, and compared it with skin conductance responses during threat anticipation and simultaneous fMRI. Participants (n=60) completed a threat-of-shock paradigm requiring goal-directed action. Cardiac contractility increased during threat anticipation, covaried with skin conductance responses, and independently predicted self-reported emotional intensity. Critically, threat-related increases in contractility-but not skin conductance-tracked threat-related modulation of activation in dorsomedial prefrontal cortex, posterior parietal cortex, and cerebellum, with contractility-modulated cerebellar activation predicting faster motor responses under threat. These findings establish TREV-derived cardiac contractility as a physiological signal linking sympathetic drive with neural responding, emotional experience, and adaptive behavioral mobilization during emotion-guided action.