The measurement of body currents

IN these days of supersensitive amplifiers and recording apparatus, it is very tempting to define life and death in terms of electrical activity. Whether or not this concept is accurate, we can, on present knowledge liken living tissue to a B-battery and dead tissue to a burned out generator. The function of living tissue, however, is so closely allied with its electrical activity that knowledge of the latter has given us better understanding of the working of the human body. Great names in electrical engineering contributed to our knowledge of the physiology of tissues. Galvani in 1780 made the really startling observation that the muscle of a frog´s leg could be made to contract when stimulated with the voltage from the crude Voltaic pile. That the muscle itself, on contracting, gave off a charge of its own was shown in 1870 by D´Arsonval, who noted the deflection of the needle when the muscle contracted across the poles of his galvanometer. Summary D.C. potentials are associated with static cellular life and are a product of metabolism. A.C. potentials are associated with many tissues controlling or responding to movement. Brain tissue is the most highly developed and exists normally in a state of constant, irregular electrical activity.