A toposcopic display system applied to neurophysiology

The cathode-ray oscilloscope is especially suited to the display of information as a graph of voltage or current plotted against time. This paper considers the advantages and disadvantages of this method of recording. It is shown that when simultaneous records must be made from signal sources which have a spatial separation, interpretation of data in Cartesian co-ordinates is invariably difficult and sometimes impossible. A method is described whereby the outputs from 24 amplifying channels are displayed in spatial co-ordinates with provision for indicating the frequency, phase and time relations of each channel. Applications of the method to neurophysiological problems are briefly discussed, particularly in relation to the study of activity evoked in the brain by rhythmic sensory stimulation. It is emphasized, however, that the method is by no means confined to such problems, although the apparatus was designed for physiological applications. Studies of the distribution of current flow in semi-conductors have been made using the system and it is thought that there are applications of the method in other fields of electronics, for example, in vibration analysis.