PHYSIOLOGICAL MECHANISMS UNDERLYING THE ELECTRICAL ACTIVITY OF THE BRAIN

Abstract

Progressive changes in the wave frequency of the electro-encephalogram in human subjects under progressive stages of anoxia, hypoglycemia, and pentothal anesthesia, and in one instance of fainting are described. The frequencies are analyzed by the use of the electronic analyzer of Walter. The changes brought about by oxygen lack and hypoglycemia where consciousness is preserved consist of a progressive slowing of the alpha rhythm. The changes found in loss of consciousness by pentothal anesthesia are more complex and are discussed in relation to the changes found in the subject who fainted in the absence of the drug. When the results are reviewed in the light of existing hypotheses as to physiological mechanisms underlying the electrical activity of the brain the author states that the frequency changes seen in oxygen deprivation and hypoglycemia are changes produced in the same neuronal population of the cortex rather than a replacement by activity from other cell units. The data is thought to be consistent with a postulate that the alpha rhythm results from the repetitive action of cells in neurone chains, that the rate can be modified within certain limits by metabolic changes in the respiration of cortical cells, that it can be disrupted by any agent which inactivates a link in the chain, and that it is thrown out of synchrony by the arrival of action potentials originating as sensory impulses.