Depressive effects of ECS as related to the peak intensity of unidirectional square-wave ECS.

Abstract

Hayes (3) and Hovorka (4), using 60-cycle alternating current, have found the amount of behavioral depression produced by a series of electroshock convulsions to be inversely related to the intensity of the current. Pierce, Russell, and Patton (8) have studied the effects of various types of ECS stimulation upon the absolute thresholds of the convulsive behavior. Liberson (6, 7), Woodbury and Swinyard (9, 10), and Arieff (1) have found that convulsions can be produced with much less electrical energy and lower peak intensities when unidirectional square-wave stimulation is used than is possible with 60-cyclc alternating current. This increased efficiency makes possible the use of very high intensity currents of short duration. Doctor (2) has recently directly compared behavioral effects produced by unidirectional square-wave and sine-wave currents and has found less disruption of behavior with unidirectional ECS.The present experiment was designed to study the effects of a greatly increased range of intensity values and to relate the depressive effects of ECS to the peak intensity of unidirectional square-wave ECS. The pulse frequency, pulse duration, and total stimulus duration were chosen on the basis of earlier experiments. In earlier studies, it was found that the depressive effects resulting from ECS did not significantly change as the pulse frequency was varied from 300 to 600 pulses per second. Increases in stimulation time above that needed for the production of convulsions, resulted in no additional behavioral depression. A pulse duration of 700 ^sec. was found to result in the smallest amount of depression (5).