MODIFICATION OF THE CORTICAL FREQUENCY SPECTRUM BY CHANGES IN CO2, BLOOD SUGAR, AND O2

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Abstract
The responses of the electrical activity of the human cortex to alterations in normal blood constituents were analyzed with the Grass frequency analyzer. Decrease in CO2 content in the internal jugular blood is associated with a shift in energy distr. in the cortical frequency spectrum toward the slow side; an increase with a shift in energy distr. to the fast side; these effects become less marked with extremely high or extremely low CO2 tensions. O2 and glucose, on the other hand, can be varied within wide limits with little change in the cortical frequency spectrum but when the O2 saturation or glucose conc. in the internal jugular falls to a critically low level, there is a sudden shift of energy distr. to the slow side. With exceedingly high concs. of glucose, the energy distr. in the cortical frequency spectrum shifts toward the fast side. Expts. on rabbits indicate that the effects of high O2 tension are similar to the effects of high concs. of glucose. The electrical activity of the cortex is apparently a manifestation of the activity of a great number of chemical oscillators having different natural periods. Though differing in their periods, these oscillators tend to respond similarly to any given factor. A factor which affects one frequency tends to affect all frequencies in the same direction, though not necessarily to the same degree.