Autonomic cardiac control. III. Psychological stress and cardiac response in autonomic space as revealed by pharmacological blockades

TLDR

Behavioral contexts elicit diverse autonomic response modes, ranging from reciprocal to coactive or independent changes in autonomic divisions. The study examined how the heart’s autonomic control reacts to psychological stressors using quantitative blockade analysis and noninvasive heart period variability and systolic time interval indices. The authors employed quantitative analysis of single and double autonomic blockades and noninvasive indices derived from heart period variability and systolic time intervals. Pharmacological blockades revealed increased sympathetic and decreased parasympathetic control during speech stress, mental arithmetic, and reaction‑time tasks, with autonomic branches responding independently and exhibiting stable individual differences; noninvasive indices mirrored these results, highlighting individual variability, the quantitative approach’s advantages, and the importance of validity estimates.

Abstract

Abstract Behavioral contexts can evoke a variety of autonomic modes of response, characterized by reciprocal, coactive, or independent changes in the autonomic divisions. In the present study, we investigated the reactive autonomic control of the heart in response to psychological stressors, using quantitative methods for analyzing single and double autonomic blockades, and through the use of noninvasive indices based on heart period variability and systolic time intervals. Analysis of the effects of pharmacological blockades revealed an overall pattern of increased sympathetic and decreased parasympathetic control of the heart during speech stress, mental arithmetic, and a reaction‐time task. Unlike the classical reciprocal sympathetic‐parasympathetic response to orthostatic challenge, however, the responses of the autonomic branches to stress were uncorrelated. This reflected notable individual differences in the mode of autonomic response to stress, which had considerable stability across stress tasks. The putative noninvasive indices of sympathetic (preejection period) and parasympathetic (respiratory sinus arrhythmia) control changed in accord with the results of pharmacological blockades. Together, these results emphasize the substantial individual differences in the mode of autonomic response to stress, the advantages of a quantitative approach to analyzing blockade data, and the importance of validity estimates of blockade data.