Факультет біології, географії та екології
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Item Cognitive Loading-Related Changes in the Coherence of EEG Rhythms in Hard-of-Hearing Adolescents(2016) Shkuropat, A. V.; Шкуропат, А. В.We recorded EEG activity in 82 12- to 15-year-old adolescents suffering from sensorineural hearing loss (II or III degree) and 80 secondary-school similar-age pupils with normal hearing. Four pairs of recording electrodes (frontal, temporal, parietal, and occipital) were used. The recording was performed under resting conditions and during the performance of the Raven test, which provided the action of cognitive loading. In hard-of-hearing boys and girls in the resting state, the number of lead pairs with significant or high coherence of oscillations of the EEG rhythms (coherence coefficients, CC, 0.51 to 0.70 and 0.71 to 1.00, respectively) usually exceeded the respective figures in normally hearing adolescents. In boys of both groups performing the cognitive test, the number of lead pairs with the CCs exceeding 0.50 increased in most cases. This was especially significantly manifested with respect to theta activity in hard-of-hearing boys; a focus of intense coherence of theta oscillations was formed in subjects of this group in the right temporal area. In girls of both groups, cognitive loading usually did not induce considerable increases in the coherence of EEG rhythms; the number of lead pairs with CC values > > 0.50 either remained unchanged or even decreased. Thus, hard-of-hearing adolescents (especially boys subjected to cognitive loading) demonstrated an intense trend toward increase in coherence relations between remote cortical loci (generalization of coherence), i.e., toward the formation of more extensive associative networks. Changes in the spatial organization of coherent relationships under the action of cognitive loading demonstrate certain gender specificity.Item Coherent Relations in EEGs of Adolescents with Partial Hearing Loss under Conditions of an Orthostatic Test(2018) Shkuropat, A. V.; Шкуропат, А. В.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.