N is the number of subjects; d and s are the right and left hemispheres, respectively. + – correlation of parameters of the SGP with monopolar SCP in the occipital lead, in other cases – with local SCP in the occipital lead.
The table shows that in healthy subjects of young and middle age correlations are negative, as well as in patients with BA. This corresponds to the reciprocal relationship that exists between the CPA and the excitability of nerve cells. With increased excitability of neurons, their high activity is noted. It is accompanied by a decrease in pH, which in turn reduces the excitability of nerve cells. Therefore, a negative correlation between the UPP value and the amplitude of the SGP may be associated with a decrease in the excitability of neurons, accompanied by a decrease in the amplitude of the SGP during the acidification of the nervous tissue, which is reflected in the growth of the UPP.
In elderly subjects, an increase in the amplitude of component P3 correlates with an increase in SCP, which may be due to a change in the nature of the feedback between SCP and the amplitude of the VEP for these components, for example, due to a decrease in the sensitivity of nervous tissue to acidification.
In the correlation analysis, it is customary to evaluate the influence of one or another factor by the square of the correlation coefficient. On the basis of this, it can be assumed that the effect of changes in the AAC, reflected in constant potentials, on the amplitude characteristics of the evoked potentials does not exceed, as a rule, 40%. A significant factor affecting the SGP and SCP may be the effect of metabolic by-products affecting the CRP. A decrease in pH decreases the amplitude of the focal response in sections of the hippocampus and, conversely, an increase in pH increases the excitability of neurons (U. Bonnet et al., 2000). The change in acid-base balance is the most significant factor determining the relationship between the characteristics of SCP and SGP.