One other distinctive feature of the reorganization of intercentral interactions in case of regulatory structure damage is the reciprocal nature of changes in the combinations of brain biopotentials (Boldyreva, 2000).
Whereas data of visual and spectral assessment of EEG and evoked potentials phenomena is greatly productive in the search for prognostic criteria of the development of pathological states with loss of consciousness (Danze, Brulem, & Haddadm, 1989; Gnezditsky, Popova, & Fedin, 1996; Ogura, 1992; Rath & Klein, 1991), analysis of EEG intercentral interactions was found to be most productive for the study of systemic cerebral maintenance of various forms of disturbed consciousness (Dobronravova, 1990; Grindel, 1985; Sharova, 1999; Sharova, Kulikov, & Zaitsev, 1997).
With the aid of such an approach, it has been shown that one of the neurophysiological mechanisms of consciousness depression and the development of comatose states in patients with brain tumors is the destruction of intercentral connections of cerebral electrical processes with the decrease of mean levels of EEG coherence.
The study of the dynamics of intercentral interactions in the process of the recovery of consciousness (from coma to clear consciousness) carried out on the parameters of mean levels of EEG coherence in patients with severe craniocerebral trauma has lead to the revelation of several common mechanisms of this process, as displayed in Figure 5.
Such a direction of changes in intercentral interactions probably reflects the transition to a "frontal regulation type," typical for healthy subjects, as an essential condition for successful recovery of consciousness (Sharova, 1999).
In models on increasing depression of consciousness or recovery of cerebral activity, it has been shown that the reorganization of intercentral interactions, including interhemispheric EEG asymmetry, is dynamic in nature and is determined not only by hemispheric specificity of cortical elements, but also by the state of median regulatory brainstem-diencephalic structures.
As discovered, during the process of post-comatose mental recovery with the dynamic nature of reorganization of intercentral interactions, there is a reflection of the properties of the brain functional systems providing each stage of recovery.
These lesions of pathological EEG pattern generation not accompanied by structural changes (according to CT and MRI) or severe corresponding focal neurological symptoms can markedly alter the nature of the interaction of separate brain regions and determine the development of new altered intercentral interactions.