Abnormal activation of temporoparietal language areas during phonetic analysis in children with dyslexia.

Event-related magnetic fields were recorded using magnetoencephalography in children with (n=12) and without (n=11) dyslexia while they discriminated between pairs of syllables from a voice onset time series (/ga/-/ka/). Nonimpaired readers exhibited left-hemisphere predominance of activity after the resolution of the N1m, whereas children with dyslexia experienced a sharp peak of relative activation in right temporoparietal areas between 300 and 700 ms post-stimulus onset. Increased relative activation in right temporoparietal areas was correlated with reduced performance on phonological processing measures. Results are consistent with the notion that deficits in appreciating the sound structure of both written and spoken language are associated with abnormal neurophysiological activity in temporoparietal language areas in children with dyslexia.