Factors Controlling Brain Potentials

I shall consider in this paper some of the results and particularly the problems which have emerged from the electrical study of the central nervous system, and shall draw upon facts established in other laboratories as well as in our own to document the general theses developed. (In the bulk of our own work on the cat a concentric needle electrode has been located in particular brain regions with the Horsley-Clark instrument, and potentials, after appropriate amplification by a resistance-capacity amplifier with large condensers, observed via the loud speaker or photographed from the cathode ray tube. Concentric or bipolar wire leads have also been used in studies on the frog, and the usual plate electrodes applied to forehead and occiput in the case of the human. All the figures are cathode ray traces, the time-axis being supplied by the moving film.)