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Abstract:
Rapid auditory processing (RAP) skills are believed to
underlie successful language acquisition. Moreover, there is much
evidence supporting the idea that developmental dyslexia and
Specific Language Impairment (SLI) are characterized by a deficit
in the ability to process rapidly presented, brief, auditory
stimuli, and such deficits are observable early in development.
Investigations of RAP in a rodent model of SLI have shown that
adult rats with induced cerebrocortical microgyria are deficient
compared to sham animals. In the present study, a reflex
modification paradigm was used to investigate potential RAP shifts
in developing microgyric and sham rats beginning on P15, P35, and
P64. It was found that gap detection thresholds did not
significantly differ between lesioned and sham subjects at any age,
but decreased over the course of development: from 10 20 msec in
the P15 and P34 groups, to 5 10 msec in the P64 group. In addition,
lesioned rats were unable to discriminate computer generated
speech-like stimuli /wa/ vs. /ba/ in the P15 group, as compared to
shams. These results further support the hypothesis that RAP is
impaired in rats with induced cerebrocortical microgyria, and this
deficit is evident in very young animals.
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