Electrodermal response - Correlation between potential and conductance

Abstract

Electrodermal activity (EDA) is well known for sensing emotional activity and autonomous nerve activity. The changes are easily detected by means of electrical measurements, and since the sweat ducts are predominantly resistive, a low-frequency conductance measurement is appropriate for measurement of exogenous EDA. The endogenous measurements are carried out as dc potential measurements. The main purpose of this study was to compare the endogenous and exogenous responses in order to acquire a better understanding of the underlying mechanisms. Measurements of exogenous and endogenous EDR were conducted simultaneously in the palms of healthy volunteers, using the same electrodes for both measurements. The results suggest a high degree of correlation between skin impedance and skin potential, even if a bi-phasic skin potential response (SPR) wave occurred for some people. A possible interpretation of these results, is that the endogenous EDR activity is produced by streaming potentials in the sweat ducts. The exogenous pulse, on the other hand, will be due to the shunting effect of the filled sweat ducts, and the conductance will not completely return to baseline until these ducts are drained. © Springer-Verlag 2007.