ELECTRODERMAL ACTIVITY REVEALS RESPIRATORY AND SLOWER RHYTHMS OF THE AUTONOMIC NERVOUS-SYSTEM

Electrodermal Activity (EDA) was measured in 55 subjects during (1) an alarm reaction, (2) mental load, and (3) physical load. In 34 subject s, not only was a transient response observed, but also, oscillatory p atterns chararcterizing short term variations of EDA. The durations of these oscillations varied between 3-16 s. Most commonly, they were ap proximately within the frequency range of respiration, or lower, at ab out 0.1Hz. The EDA-rhythms were also related to the arterial blood pre ssure. They were, however, not strictly synchronized with respiration or with the blood pressure waves. We conclude that assessment of EDA i n combination with fluctuations of the heart rate, and also, if possib le, arterial blood pressure, may turn out to be a useful tool in the e valuation of the interaction between different regulatory processes th at are realized by the common brainstem system.