Cortical-subcortical interactions and the regulation of the functional state of the brain in acute hypoxia in humans.

The mechanisms regulating the functional state (FS) of the brain were studied in humans in conditions of dosed acute hypoxia (breathing a mixture of 8% oxygen in nitrogen for 15-25 min). The dynamics of the FS of the brain due to changes in the balance of the activities of brain regulatory structures in hypoxia were reflected in rearrangements of EEG spatial relationships (factor and cluster analysis of EEG crosscorrelation matrixes) and the redistribution of intracerebral locations of electrically equivalent dipole sources (EEDS), with increases in EEDS density in the projections of the medial and basal parts of the temporal lobes of the hemispheres (EEDS tomography data). Changes in cortical-subcortical interactions were characterized by a decrease in the tone of the activatory brain system, a decrease in the inhibitory control of subcortical structures by neocortical formations, and activation of limbic system and hypothalamic structures. Switching of the integrative regulatory mechanisms from the cortico-thalamic level to the limbic-diencephalic level may allow release of the energy-consuming nonspecific components of hypoxic stress and more stable regulation of physiological parameters by the major vital systems in conditions of increasing oxygen deficit.