EEG topography: Encyclopedia II - EEG topography - History

EEG topography - History

EEG brain topography was invented by Walter Grey Walter, who, in 1936, proved that, by using a larger number of electrodes pasted to the scalp, each one having a small size, and a triangulation algorithm, it was possible to identify abnormal electrical activity in the brain areas around a tumor, and diminished activity inside it. Impressed with the possibilities of building bidimensional maps of the EEG activity over the brain surface, Grey Walter invented the toposcope in 1957.

This was a remarkably complex device and showed Grey Walter's inventiveness (besides being a physician, he was also an engineer). It had 22 cathode ray tubes (similar to a TV tube), each of them connected to a pair of electrodes attached to the skull. The electrodes (and their corresponding tubes) were arranged in a bidimensional geometrical array, such as that each tube was able to depict the intensity of the several rhythms which compose the EEG in a particular area of the brain (the frontal, parietal and occipital lobes, etc.). This array of CRT tubes, were photographed face up, so that a kind of phosphorescent spiral display showed simultaneously which kind of rhythm was present in a particular part of the brain.

Adapted from the Wikipedia article "History", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki