Auditory deficit as a consequence rather than endophenotype of specific language impairment: electrophysiological evidence

Are developmental language disorders caused by poor auditory discrimination? This is a popular theory, but behavioural evidence has been inconclusive. Here we studied children with specific language impairment, measuring the brain's electrophysiological response to sounds in a passive paradigm....

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Bibliographic Details
Published in:	PloS one 2012-05, Vol.7 (5), p.e35851-e35851
Main Authors:	Bishop, D V M, Hardiman, Mervyn J, Barry, Johanna G
Format:	Article
Language:	eng
Subjects:	Acoustics Adolescent Adolescents Auditory discrimination Auditory Diseases, Central - etiology Behavior Biology Brain Brain research Child Children Comparative analysis Electrodes Endophenotypes Event-related potentials Evoked Potentials, Auditory Experimental psychology Female Humans Impairment Language Language Development Disorders - complications Language Development Disorders - physiopathology Language disorders Male Medicine Models, Biological Native languages Neurophysiology Parents Quantitative psychology Studies Syllables Topography
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Summary:	Are developmental language disorders caused by poor auditory discrimination? This is a popular theory, but behavioural evidence has been inconclusive. Here we studied children with specific language impairment, measuring the brain's electrophysiological response to sounds in a passive paradigm. We focused on the T-complex, an event-related peak that has different origins and developmental course from the well-known vertex response. We analysed auditory event-related potentials to tones and syllables from 16 children and 16 adolescents with specific language impairment who were compared with 32 typically-developing controls, matched for gender, IQ and age. We replicated prior findings of significant reduction in Ta amplitude for both children and adolescents with specific language impairment, which was particularly marked for syllables. The topography of the T-complex to syllables indicated a less focal response in those with language impairments. To distinguish causal models, we considered correlations between size of the Ta response and measures of language and literacy in parents as well as children. The best-fitting model was one in which auditory deficit was a consequence rather than a cause of difficulties in phonological processing. The T-complex to syllables has abnormal size and topography in children with specific language impairment, but this is more likely to be a consequence rather than a cause of difficulties in phonological processing.
ISSN:	1932-6203 1932-6203