Interlinked positive and negative feedback loops design emotional sweating.

BACKGROUND The stereotyped nature of the skin conductance response (SCR) waveform has recently inspired several dynamic modeling approaches to the process of SCR. The suggested models differ: (i) in the order of the linear differential equation representing the process, and (ii) the neurobiological interpretation of the system parameters. While several research groups consider the sympathetic sudomotor nerve activity as the input signal in their models of the SCR, we assume that the initial neural event and feedback regulatory mechanisms that we can comprise with our models take place in the central brain structures. Here we demonstrate a refinement of the system identification procedure with skin conductance response signal, in order to test the thesis of the central meaning of the model's parameters. SUBJECTS AND METHODS The method consists in the application of the system identification procedure in the MATLAB® software environment in analyzing the SCR. Eleven short stories have been used to elicit emotional arousal in 27 healthy participants. RESULTS The method for mathematical modeling of the SCR here proposed provides not only the best fitting with empirical SCR signals that has ever been reported, but also insight into the unique underlying control process and the hidden neural input to the SCR system. Through the system identification procedure we showed that there are two interlinked positive and a negative feedback loop which shape the SCR. The control process of SCR showed a linear and a within stimulus-type time invariant. CONCLUSION The findings argue in favor of the central nervous system interpretation of the parameters in the presented dynamic model of the SCR response. This encourages the idea of developing a method that could enable estimation of the central nervous system regulatory processes relying on the psychophysiological data.