Changes in the high-frequency activity of rabbit brain biopotentials in the state of "animal hypnosis"

Spectral EEG analysis studies showed that in the state of "animal hypnosis," the known increase in the power of biopotentials in the delta frequency range (0.3-3 Hz) and decrease in the theta range (4-8 Hz) were accompanied by an increase in the sigma range (12-17 Hz) by a factor of 2-4 and a decrease in the gamma range by a factor of 1.5-2, particularly in the band 40-70 Hz. These changes were more marked in the anterior areas of the cerebral cortex. The effects of the hypnotic state on pharmacologically (ketamine) induced increases in gamma activity of cortical origin were studied. Administration of subanesthetic doses of ketamine to rabbits induced motor arousal, while brain electrical activity showed longlasting (up to 2 h) increases in gamma activity. Creation of the hypnotic state on the background of ketamine produced a virtually instantaneous rearrangement of the power spectrum, which sharp increases in values in the slow-wave frequency range and a decrease in gamma activity, which returned to the baseline level. Thus, creation of the hypnotic state eliminated the specific ketamine-induced rearrangements of biopotentials, suggesting that animal hypnosis has stabilizing and to some extent protective effects in behavioral states accompanied by hyperlocomotion and stress. © 2011 Springer Science+Business Media, Inc.