Brain Abnormalities in Language Disorders and in Autism
Section snippets
Asymmetry
The populational predominance of leftward lateralization of language functions has made the study of asymmetry attractive in autism and SLI, because it is known that there is a higher frequency of ambidextrousness, left-handedness, or right hemisphere language dominance in individuals who have language disorders and autism. This question has been pursued in imaging studies of autism and SLI subjects, but it has been addressed differently in the two groups. We address large-scale, local, and
Sensory perception deficits in autism
Autism has been linked with impairments in simple sensory perception early in the hierarchy of cortical processing, in the visual [76], [77], [78], [79], [80], [81] and auditory [82], [83], [84], [85], [86], [87], [88] domains, and to some extent also in the somatosensory domain [89], although those data are so far mostly anecdotal. To date, the correlation between these sensory impairments and the behavioral characteristics of autism remains unknown. More specifically, the extent to which some
Neuropathology and pathophysiologic considerations
Moving down from macroanatomy to tissue rather than up to function in the biologic hierarchy leads to neuropathology and cellular and molecular pathophysiology. There is a modest amount of neuropathologic literature in autism, almost none in SLI, and some in dyslexia. Findings in dyslexia have included ectopia, altered asymmetries, abnormal minicolumns [116], and abnormalities in the magnocellular system. Animal models developed to pursue some of these findings show an association between
Summary
We have reviewed local and widespread anatomic changes in SLI and autism, and substantial but not complete similarities between the two disorders, and we have reported suggestive sensory processing abnormalities across domains. The findings we have reported go substantially beyond the structural and functional domains that would be uniquely altered if these disorders were based on genes or pathophysiologic processes that specifically targeted the neural substrates of language processing. They
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This work was supported by NS48455 from NINDS, the Cure Autism Now Foundation, and the Bernard Fund for Autism Research.