Бюллетень сибирской медицины (Aug 2019)
About the use of omega-electroencephalography to estmate functional and metabolic state of nervous tissue of the brain during hyperventilation
Abstract
Objectives. The aim of this study was to investigate diagnostic capabilities of a new electrophysiological method of omega-electroencephalography in the estimation of change in functional and metabolic state of the cells of nervous tissue during ischemic adaptation.Materials and methods. Brain ischemia was modeled based on a hyperventilation test (HVT). Recording and analysis were made on concomitant changes in direct current potential level (DCPL) and EEG in 38 derivations for the same test person in a fourfold-replicated HVT.Results. Brain ischemia that occurs during volitional hyperventilation was initially followed by DCPL negativation (negative shift) (0.5–1 mV) and increase in amplitude of all EEG waves. Cessation of HVT and return to initial DCPL were followed by positivation (positive shift) of DCPL (about 1 mV), combined also with high-amplitude EEG waves. Adaptation to hypoxia and ischemia, modeled using replication-based HVT, and improvement of brain resistance to these unfavorable factors manifested themselves first in a short-term electropositive deviation of DCPL at the start of the test followed by DCPL positivation reduction and then in complete substitution of electronegative response to positive shift in DCPL (about 0.5 mV) during the test.Conclusion. The analysis of concomitant changes in DCPL and EEG during and after hyperventilation and literature data analysis suggests that HVT was initially responded to by depolarization in neocortical nerve cells, combined with intensification of neuronal activity. Activation of compensatory mechanisms, resulting in improvement of nerve cell resistance to ischemic conditions, is associated with ischemic depolarization followed by hyperpolarization, and enhancing adaptive capabilities of brain cells manifest themselves in substitution of cell membrane depolarization to hyperpolarization in response to unfavorable factor, also combined with intense neuronal activity.
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