Potential distribution analysis I. A new technique for the analysis of electrophysiological phenomena

A new technique for the study of the electroencephalogram permits of a differentiation between electrical activity produced by stationary sources and that due to changing source configurations.

Abstract

1. A new technique for the study of the electroencephalogram is described; it may be applied also to other electrophysiological phenomena. It permits of a differentiation between electrical activity produced by stationary sources and that due to changing source configurations. 2. The method has two main steps. The first of these consists of measuring ordinates of the EEG recorded from a row of equally spaced electrodes at successive time instants. From these measurements the potential distributions at these instants can be reconstructed. 3. The second step involves a transformation of these measurements. This is done by dividing the measurements for each time instant by the measurement corresponding to a chosen channel, the same channel being used for any one group of time instants. This procedure we call normalising the potential distribution. 4. In some observed EEG phenomena the resultant series of normalised distribution graphs show congruence suggesting that they result from the activity of stationary sources. In other phenomena the graphs are not congruent; here interpretations in terms of moving sources may be indicated. These conclusions deduced from theory are supported by experiments using electrolytic models. 5. The results suggest that the technique may find a further application in the detection of time of onset and termination of certain EEG phenomena. 6. The possibility of the existence of a quantitative relation between the derived potential distributions and the position of source configurations is discussed in a second paper.