NEUROBEHAVIORAL DEVELOPMENT IN NORMAL AND LI/RD CHILDREN

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Our long term goals are to study biological constraints and the role of experience in the formation of neural systems relevant to language and cognition. Our approach will be to compare cerebral functions during sensory, cognitive and language tasks in children at different ages and different stages of language and cognitive development. Additional comparisons between normal children and children who are specifically language-impaired and reading disabled (LI/RD) will also help to separate age-related from language-relevant aspects of neural development, and will permit an assessment of the neurobehavioral functions that have been implicated in the deficits that LI/RD subjects (Ss) display. We will record event-related brain potentials (ERPs) from over several brain regions while normal children aged 4-19 years and LI/RD children and matched controls aged 10-13 years process specific kinds of sensory, cognitive and language information. The hypotheses to be tested in the five series of proposed studies include: (1) The neural systems associated with grammatical processing develop later, are more dependent on specialized system within the left hemisphere, and are more impaired in LD/RD Ss than are those associated with semantic processing, (II) LI/RD Ss display a deficit in the elaboration and subsequent recognition of auditory language material, (III) Priming of semantic and phonological lexical information involves different neural systems; the former are intact but the latter are deficient in LI/RD Ss, (IV) Different neural systems mediate language and non-language cognitive processes at all ages and levels of development; the specialization of the right hemisphere for spatial attention and face perception is preceded by and depends upon the development of left hemisphere specialization for language and (V) LI/RD populations are impaired in the ability to process rapidly presented non-language auditory and visual stimuli. The proposed research is pointed, in the long run, toward an understanding of the optimal nature and timing of education for normal and language-impaired populations.