Average Evoked Responses to Somatic Stimulation in the Cat: Changes in Relation to State of Vigilance

Abstract

Publisher Summary In a study, electrodes were implanted into primary or associative structures of four cats. At the level of the thalamus, the structures were the center median, the VPL, and the VL; and at the level of the cortex, the area of the anterior sigmoid gyrus, the lateral extremity of the cruciform gyrus, and the area marginalis anterior. Spontaneous activities, evoked by stimulation of the radial contralateral nerve, were recorded on to magnetic tape from cats that were awake, drowsy, and asleep. Averages of 50 responses were computed for each condition; data were also collected from these same animals under chloralose or Nembutal anesthesia. It was observed that the average amplitude of the first positive deflection evoked in primary cortical areas is small, while the cat is awake; it increases slightly as the animal falls asleep and is in the sleep-slow phase; and it increases significantly during the sleep-fast phase. The findings were compared with those previously reported; in particular, the effects of chloralose anesthesia were compared with the changes in evoked potentials that occur during the sleep-slow phase.