Cognitive Loading-Related Changes in the Coherence of EEG Rhythms in Hard-of-Hearing Adolescents

Abstract

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.