Neurophysiological Analysis of Speech Perception in 2.5 to 3.5-Year-Old Orphans and Children Raised in a Family
2014 (English)In: Neurophysiology (New York), ISSN 0090-2977, E-ISSN 1573-9007, Vol. 46, no 1, 79-87 p.Article in journal (Refereed) Published
In 2.5-3.5-year-old orphans (n = 41) and children raised in a family (n = 50), we examined specificities of speech perception-related changes in the spectral power density (SPD) of the EEG rhythms. Changes in the SPDs of the theta-, alpha-, beta-, and gamma-rhythms in 16 EEG leads where estimated at presentation of a meaningful speech fragment record (short poem) and of a reversed record of the same signal (direct and reversed speech, respectively). The Bayley Scales of Infant and Toddler Development III demonstrated the existence of noticeable delays in the development of speech in orphans. Comparison of background EEGs and EEGs in the course of listening for direct speech showed that the alpha-rhythm is desynchronized, while the theta-, beta-, and, especially, gamma-oscillations are synchronized upon perception of the above stimulus. In this case, children raised in a family demonstrated significant increases in the gamma-rhythm SPD in 13 leads of both hemispheres; in orphans, this was observed only in 8 loci localized mostly in the left hemisphere. In children of both groups, listening for reversed speech induced mostly desynchronization of all EEG rhythms with the greatest drops in the gamma SPD mostly in the frontal and left temporal leads. Comparison of SPDs of the EEG components (rhythms) at listening for direct and reversed speech demonstrated that powers of theta-, beta-, and gamma-oscillations increased at presentation of a direct (comprehended) speech in children of both groups. In children raised in families, greater SPDs of the gamma-rhythm were observed in 13 leads (differences were most significant in the frontal parts of the left hemisphere). In institutionalized children, the number of leads with significant increments of the gamma-rhythm power was significantly smaller (only 9). It is supposed that smaller increases in the SPD of of gamma-range oscillations in orphans are related to deviations in the processing of a semantic component of speech perception. This can result from insufficient development of cerebral neuronal networks responsible for processing of verbal information.
Place, publisher, year, edition, pages
2014. Vol. 46, no 1, 79-87 p.
speech perception, EEG rhythms, orphans, direct and "reversed" speech
IdentifiersURN: urn:nbn:se:uu:diva-227135DOI: 10.1007/s11062-014-9409-6ISI: 000335143800011OAI: oai:DiVA.org:uu-227135DiVA: diva2:728741