Patterns of Sympathetic Responses Induced by Different Stress Tasks
M Fechir*, 1, T Schlereth1, T Purat 1, S Kritzmann1, C Geber1, 3, T Eberle1, M Gamer2, F Birklein1
1 Department of Neurology, University of Mainz, Langenbeckstrasse 1, 55101 Mainz, Germany
2 Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20248 Hamburg, Germany
3 Department of Physiology, University of Mainz, Duesbergweg 6, 55128 Mainz, Germany
Stress tasks are used to induce sympathetic nervous system (SNS) arousal. However, the efficacy and the patterns of SNS activation have not been systematically compared between different tasks.
Therefore, we analyzed SNS activation during the following stress tasks: Presentation of negative, positive, and – as a control – neutral affective pictures, Color-Word interference test (CWT), mental arithmetic under time limit, singing a song aloud, and giving a spontaneous talk. We examined 11 healthy subjects and recorded the following SNS parameters: Activation of emotional sweating by quantitative sudometry, skin vasoconstriction by laser-Doppler flowmetry, heart rate by ECG, blood pressure by determination of pulse wave transit time (PWTT), and electromyographic (EMG) activity of the trapezius muscle. Moreover, subjective stress ratings were acquired for each task using a visual analog scale.
All tasks were felt significantly stressful when compared to viewing neutral pictures. However, SNS activation was not reliable: Affective pictures did not induce a significant SNS response; singing, giving a talk and mental arithmetic selectively increased heart rate and emotional sweating. Only the CWT globally activated the SNS. Regarding all tasks, induction of emotional sweating, increase of heart rate and blood pressure significantly correlated with subjective stress ratings, in contrast to EMG and skin vasoconstriction.
Our results show that the activation of the SNS widely varies depending on the stress task. Different stress tasks differently activate the SNS, which is an important finding when considering sympathetic reactions - in clinical situations and in research.
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.5/), which permits unrestrictive use, distribution, and reproduction in any medium, provided the original work is properly cited.
* Address correspondence to this author at the Neurologische Klinik, Universität Mainz, Langenbeckstrasse 1, D-55101 Mainz, Germany; Tel: +49-6131-174588; Fax: +49-6131-175570; E-mail: email@example.com