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Abstract:
Abstract: Developmental dyslexia affects approximately
10-20%of the population. Previous neuroimaging studies have shown
decreased activity in temporo-parietal brain areas in adults with
developmental dyslexia while engaged in phonological processing. In
addition, we have shown that adults with developmental dyslexia
have a disrupted response to non-linguistic rapid auditory stimuli.
We examined the neural response to phonological processing and
rapid auditory processing in 20 children (aged 8-12) with
developmental dyslexia. In the study we used whole brain fMRI (18
axial slices, 6 mm slices with 0 mm skip) in two separate scans.
One scan involved perception of nonspeech analogues with rapid (40
ms) or slowed (200 ms) auditory transitions. Stimuli were presented
every 2.85 seconds using a clustered volume acquisition such that
stimuli were presented during a 'quiet period' between scanning
cycles. The second scan alternated between rhyming letters,
matching letters, and matching simple lines. The dyslexic children
had a disrupted response to the rapid nonspeech analogues, as
compared to the slowed, similar to the disrupted response we have
seen in adult dyslexics. These results suggest that children with
developmental dyslexia have a disruption in the neural response to
rapid auditory stimuli.
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