In both the laboratory and the operating room we have felt the lack of a simple, accurately controlled device for faradic stimulation of the cortex. Without discussing the apparatus designed and used for this purpose, it may be said that most have one or both of the following faults: They are too complex to be used in the operating room by the "workaday" surgeon, or the currents they deliver for stimulation cannot be controlled easily enough. In the device described here, we sought graded, predetermined currents at a suitable frequency and in a satisfactory wave form.
Commercial 110 volt, 60 cycle alternating current is used to supply power. A relatively high voltage (220 volts) is delivered to the stimulating circuit. The current that may flow, however, is limited by graduated resistances, selected by a switch. These resistances are of relatively high order, as compared with the resistance of the tissue