Patent US RE34015

Apparatus for generating a topographic display of information on brain electrical activity based on responses of electrical-activity transducers placed on the skull. In different aspects, the brain is stimulated at pseudorandom intervals to produce EP responses; matrices corresponding to the electrical responses are processed to generate a statistical comparison matrix and the corresponding display map is grid sector analyzed; a series of tests is administered some of which put the brain in a simple resting state, others putting the brain in nonresting states of varying activity level; statistical comparison matrixes are generated representing the statistical difference between normal and abnormal groups at different skull locations with respect to different brain activities; significance probability maps are generated each representing the statistical difference between a patient and the normal population with respect to different brain activities; and an epileptic spike is caused, a sufficient number of data matrices is generated to capture onset of the spike, and the frame rate of display of the corresponding topographic maps is selectably changed for observing the onset.