Action potential form change of the area striata in hypothermia

Abstract

The effect of temperature on the evoked response of the visual cortex to single photic stimulation of the retina and single electrical stimulation applied to the optic nerve at temperatures ranging from 37 to 15° was investigated. In the experiments completely isolated and artificially perfused heads of cats are used. The latencies of the evoked responses to photic and electrical stimulation increased continously with decreasing temperatures. The amplitudes of the evoked responses to photic stimulation initially remained the same with a gradual decrease of temperature, later on decreasing and finally disappearing was obtained at 18–17°. However, the amplitude of the evoked responses to electrical stimulation increased with decreasing temperatures reaching a maximum at 26–23°, thereafter decreased again and finally also disappeared when the temperature reached 18–15°. Sometimes, at low temperatures, some additional deflections are to be find between the deflections 4 and 5 of the evoked response to electrical stimulation.