Effects of Cold on Evoked Cortical Potentials in the Rat

¹ From the Department of Neurological Surgery, New York University Post-Graduate Medical School, New York City

In the rat anesthetized with Nembutal, stimulation of the sciatic nerve elicited two cortical responses from the sensori-motor cortex. The characteristics of these effects were similar to the ‘primary response’ and the ‘secondary discharge’ recorded by others from the sensori-motor cortex of the cat when the sciatic nerve was stimulated. As the rat was cooled, the primary response increased in size, and the maximum amplitude of two to three times the normal value was found at the calculated brain temperature of 26° to 20°C. Although, no spontaneous electrical cortical activity was present at the calculated brain temperature of 18° to 16°C, the primary response always could be evoked down to a temperature of 15° to 13°C. On warming the animal, the primary response reappeared at 18° to 25°C.