Introduction
Moruzzi and Magoun's delineation of a diffuse brain stem activating mechanism in 194925 gave great impetus to the study of brain stem-cortical relations and nonspecific thalamocortical systems. Electrophysiological recordings from these systems have been collected primarily from subhuman species as they are nearly inaccessible to direct examination in man. Indirect confirmation of the existence of the same systems in the human brain has been derived from changes in the scalp EEG during various stages of sleep, coma, and centrencephalic epilepsy. Tracings from the scalp are complex due to the interaction of multiple mechanisms and thus do not readily allow analysis of individual components.Occasionally, naturally occurring disease affects the human brain in such a way that the resultant electroencephalogram provides information which normally remains obscured. We have followed a case of Jakob-Creutzfeldt's disease that had severe cortical and cerebellar neuronal loss but which showed relative preservation of the