Infusion of urea generated in cats a myoclonic syndrome reminiscent of the excitatory events of clinical uremia. The electrical concomitants of the clinical events were spikes and sharp wave discharges in the lower brain stem reticular formation mostly in nucleus gigantocellularis. Microelectrode recordings revealed that each "electroencephalographic spike" represented a 30 to 80 msec depolarization wave with a superimposed cluster of high frequency regenerative potentials, similar to the paroxysmal depolarization shifts described at the levels of neocortex and paleocortex. Intercollicular sections of the brain stem were without significant effect, but sections of the upper cervical cord or curare paralysis depressed the reticular paroxysmal activity. A reticulospinal loop probably represents the anatomofunctional basis of this paroxysmal activity. Urea specifically generates these phenomena since identical plasma osmolality induced by other hypertonic solutions did not produce them.