THE OHMIC PERTURBATION DURATION, AN ORIGINAL TEMPORAL INDEX TO QUANTIFY ELECTRODERMAL RESPONSES

The reactivity of the autonomic nervous system was (D.C.) recorded usi ng six parameters simultaneously. Such a device permitted to describe a new index of skin resistance response (SRR). The ohmic perturbation duration (O.P.D. index) was defined as the period during which the sub ject is effectively responding to the stimulation. O.P.D. index was ea sily quantified because the specific part of the response, showing man y fluctuations at a low resistance level, can be distinguished from th e recovery part without fluctuations or with smaller microevents of di fferent kinds. Moreover, the slope of this fluctuation is identical to that observed just before the stimulation. The comparison between the values of the O.P.D. index and classically used SRR durations enabled us to calculate the identity percentages from five other neurovegetat ive parameters. Results showed high values for the skin potential (91% ) and skin blood flow (82.5%). These values were smaller as far as ski n superficial temperature (50.5%), head (40.8%) and respiratory (46.5% ) variations were concerned. Nonetheless these last three percentages were still higher than those usually obtained with the values of the c orrelation coefficients from different, simultaneously recorded parame ters. O.P.D. index comparison with four other classical used temporal indices (recovery time, 1/3, 1/2 and 2/3 of the recovery time) show a high significant concordance in O.P.D. index opposed to aleatory one o btained with these four other durations. Thus, the O.P.D. index could be an appropriate measure of electrodermal response (EDA) allowing any stimulus to be temporaly quantified towards sympathetic activation in duced response.