Cerebral Asphyxiation and Spreading Cortical Depression

Abstract

The slow potential change which accompanies the spreading depression of cortical activity is modified but not abolished by a cerebral circulatory arrest up to 1 min. in duration. Cerebral circulatory arrest may produce, after a latent period of the order of 10 sec., small cortical potentials of varying direction. It seems possible that these potentials are identical with the much larger asphyxial depolarization potentials which can be led off from the spinal cord. Cerebral circulatory arrest elicits, after a much longer latent period (1-5 min.) a cortical negativity of considerable magnitude and sudden onset. The possibility that this potential is based on the same processes as the slow potential change accompanying the spreading depression was considered. This thesis is supported by the observation that a preceding slow potential change may suppress the appearance of the cortical asphyxial potential of long latent period.