Language is typically a highly lateralized function, with atypically reduced or reversed lateralization linked to language impairments. Given the diagnostic and prognostic role of impaired language for autism spectrum disorders (ASDs), this paper reviews the growing body of literature that examines patterns of lateralization in individuals with ASDs. Including research from structural and functional imaging paradigms, and behavioral evidence from investigations of handedness, the review confirms that atypical lateralization is common in people with ASDs. The evidence indicates reduced structural asymmetry in fronto-temporal language regions, attenuated functional activation in response to language and pre-linguistic stimuli, and more ambiguous (mixed) hand preferences, in individuals with ASDs. Critically, the evidence emphasizes an intimate relationship between atypical lateralization and language impairment, with more atypical asymmetries linked to more substantive language impairment. Such evidence highlights opportunities for the identification of structural and functional biomarkers of ASDs, affording the potential for earlier diagnosis and intervention implementation.
Open Access. The author accepted version of this work has been reproduced here according to the publishers policies.
The accepted version may be downloaded for personal use only. Permission to reproduce this version must be sought from Springer-Verlag. The definitive version of this article was published in the Neuropsychology Review, 23(3): 257-270, 2013. The final publication is available at www.springerlink.com