Components of the evoked potential in the MES auditory cortex

¹ Department of Anatomy, University of Oregon Medical School, Portland, Oregon

The electrical activity during the potential evoked by a p pulse was analyzed statistically by considering amplitude at each 3-msec. epoch a random variable. The rise in standard deviation during the evoked potential was abolished a) by local cocaine on the cortex, b) by a preceding evoked potential and c) by ischemia. The residual mean positive component, with zero standard deviation, was subtracted from the mean of the evoked potential. This yielded a positive-negative component, with which the spontaneous electrical activity is believed to interact. The evoked potential is thus described as the sum of the three random variables: a) spontaneous electrical activity, b) positive component, and c) positive-negative component, with a covariance term involving the spontaneous electrical activity and the positive-negative component.