IT IS now well known that the electroencephalogram is modified by a variety of factors influencing the physicochemical environment of the brain. Studies of the effects of such agents as carbon dioxide, oxygen tension, blood sugar, temperature and drugs have been made by many investigators on the measurable variables: per cent time present of the alpha activity, delta index, dominant frequency (usually the alpha frequency), wave amplitude or voltage and the form of the frequency spectrum. In this paper we point out why we believe that one of these measures is superior to the others for furnishing information about the chemical dynamics of the cortex and show why some current methods of analysis of frequencies in the electroencephalogram, while empirically interesting, must give discrepant results when compared with other methods.
The most conspicuous aspect of the normal electroencephalogram is usually the alpha rhythm. This is a rhythm of a specific
KAUFMAN IC, HOAGLAND H. DOMINANT BRAIN WAVE FREQUENCIES AS MEASURES OF PHYSICOCHEMICAL PROCESSES IN CEREBRAL CORTEX. Arch NeurPsych. 1946;56(2):207–215. doi:10.1001/archneurpsyc.1946.02300190077006
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