Unitary and Mass Cortical Potentials evoked by Peripheral Stimulation of Anaesthetized Rats

Abstract

A GREAT deal of research work has been carried out on the patterns of electrical activity which can be recorded from electrodes placed on the surface of the brain. In these records, certain patterns of activity can be recognized and alteration of these patterns can be used as indices of changes in the activity of the brain. The origin of the electrical waves, however, remains obscure. The mass potentials reflect changes in the degree of polarization of nerve cells and their processes in the brain matter underlying the recording electrode, but little is known concerning the site and sign of the polarity changes which are reflected in the characteristic electroencephalograph patterns. Creutzfeldt, Watanabe and Lux¹, in an analysis of some aspects of this problem, have pointed out that the same changes in the membrane potential in superficially and deeply sited units can produce opposite changes in the surface-recorded potential.