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Psychophysiology. 2018 Feb;55(2). doi: 10.1111/psyp.12986. Epub 2017 Sep 1.

Testing a linear time invariant model for skin conductance responses by intraneural recording and stimulation.

Author information

1
Division of Clinical Psychiatry Research, University of Zurich, Zurich, Switzerland.
2
Neuroscience Centre Zurich, University of Zurich, Zurich, Switzerland.
3
Department of Physiology and Pathophysiology, University of Erlangen, Erlangen, Germany.
4
Department of Clinical Neurophysiology, The Sahlgrenska Academy of Gothenburg University, Gothenburg, Sweden.
5
Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom.
6
Department of Psychiatry, Psychotherapy, and Psychosomatics, University of Zurich, Zurich, Switzerland.

Abstract

Skin conductance responses (SCR) are increasingly analyzed with model-based approaches that assume a linear and time-invariant (LTI) mapping from sudomotor nerve (SN) activity to observed SCR. These LTI assumptions have previously been validated indirectly, by quantifying how much variance in SCR elicited by sensory stimulation is explained under an LTI model. This approach, however, collapses sources of variability in the nervous and effector organ systems. Here, we directly focus on the SN/SCR mapping by harnessing two invasive methods. In an intraneural recording experiment, we simultaneously track SN activity and SCR. This allows assessing the SN/SCR relationship but possibly suffers from interfering activity of non-SN sympathetic fibers. In an intraneural stimulation experiment under regional anesthesia, such influences are removed. In this stimulation experiment, about 95% of SCR variance is explained under LTI assumptions when stimulation frequency is below 0.6 Hz. At higher frequencies, nonlinearities occur. In the intraneural recording experiment, explained SCR variance is lower, possibly indicating interference from non-SN fibers, but higher than in our previous indirect tests. We conclude that LTI systems may not only be a useful approximation but in fact a rather accurate description of biophysical reality in the SN/SCR system, under conditions of low baseline activity and sporadic external stimuli. Intraneural stimulation under regional anesthesia is the most sensitive method to address this question.

KEYWORDS:

microneurography; psychophysiological model; skin conductance; sudomotor nerve; sympathetic nervous system

PMID:
28862764
PMCID:
PMC5811801
DOI:
10.1111/psyp.12986
[Indexed for MEDLINE]
Free PMC Article

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