Coherent Relations in EEGs of Adolescents with Partial Hearing Loss under Conditions of an Orthostatic Test

Abstract

Results of the examination of transformations of coherent relations in EEGs under conditions of realization of an orthostatic test (OT) by adolescents with normal hearing and partial hearing loss (NH and PHL groups) are described. The OT performance was mostly characterized by spatial redistribution of the lead pairs with significant values of the coefficient of correlation (CC) and not by changes in the number of such lead pairs. The formation of an activity focus within posterior areas of the cortex after the OT was a general regularity in both examined groups and in all frequency ranges, independently of the existence of such a focus in the given examined group under conditions of functional rest. It was found that EEGs of adolescents with partial hearing loss were characterized by a smaller in the number of the lead pairs with significant CCs for the α rhythm due to disappearance of anterior coherent zones in both hemispheres of PHL girls; in PHL boys, this was observed only in the left hemisphere. We believe that the specificities of coherent relations in PHL adolescents under conditions of the OT may be determined by a greater tension in the adaptation systems and an insufficiency of the neocortical inhibitory systems; these deficiencies develop because of limitation of the sensory inflow to cortical neurons and, correspondingly, of a decrease in the tone of the respective neuronal networks.