Social and physiological stress elicit divergent psycho-physiological dynamics and motor cortex activation

The investigation of question whether a characteristic stress response pattern can be assessed through the level of motor cortex activation. This study compared the distinct effects of socio-psychological (Trier Social Stress Test, TSST) and physiological (Cold Pressor Test, CPT) stressors on the dynamics on heart rate (HR), blood pressure (BP), and subjective emotional state dynamics. The study had two primary objectives: (1) to assess the differential effects of these stressors by comparing the temporal dynamics of both physiological and psychological parameters; and (2) to estimate the relationship between corticospinal excitability and peripheral autonomic responses during stress. Motor evoked potentials from first dorsal interosseous were induced by stimulation of the primary motor cortex using transcranial magnetic stimulation (TMS), the temporal changes in all measures were analyzed at three time points: pre-stress baseline, immediately post-stress, and after a 15-min recovery period. Psychological stress induced a sustained increase in tension, a decrease in positive affect, and a prolonged peripheral activation (e.g., in HR, systolic BP). In contrast, physiological stress elicited a transient reaction, followed by rapid normalization and even a subsequent decrease in some psychophysiological indices. Analysis of subjective psychological reports showed that the TSST in-creased self-reported tension and decreased positive affect, in contrast to the CPT, which led to a reduction in tension and anxious-depressive emotions. TMS-measured cortico-spinal excitability showed a direct covariation with heart rate, indicating a tight functional coupling between the motor and autonomic nervous systems during physiological stress.