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

## TL;DR

This study shows that social and physical stress cause different patterns of physical and emotional responses, with social stress having longer-lasting effects.

## Contribution

The study reveals distinct psycho-physiological dynamics and motor cortex activation patterns in response to social versus physiological stress.

## Key findings

- Social stress (TSST) caused prolonged increases in heart rate and tension with reduced positive emotions.
- Physiological stress (CPT) led to transient responses followed by rapid normalization and even decreases in some measures.
- Cortico-spinal excitability was directly linked to heart rate, showing functional coupling during physiological stress.

## Abstract

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.