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Thursday, May 7, 2009
Northwest Hall (Chicago Hilton)
12:00 PM
Background: Individuals with autism spectrum disorders often exhibit atypical language patterns including delay of speech onset, literal speech interpretation, and poor recognition of social and emotional cues in speech. Previous studies have noted tendency towards left-handedness in autistic populations with increased right hemispheric processing of language in autism. We examined stability of language lateralization during the course of a language stimulus using fMRI in control and high-functioning autistic populations.
Objectives: Determine whether increased right hemispheric processing of language results from increased right hemispheric activity or decreased left hemispheric activity relative to controls.
Methods: Twenty-five right-handed subjects (13 high-functioning autistic, 12 control) were studied using auditory and visual sentence completion tasks, and areas of differential activation between groups were identified. Hand preference was measured by Edinburgh Handedness Inventory and included as a covariable in the analysis.
Results: Autistic subjects showed significantly increased activation of right Wernicke's area compared to control subjects. After adjustment to account for differences in hand preference among groups, this difference persisted. Time series traces showed that both populations initially activated both hemispheres during the course of a language stimulus, but control population showed suppression of right-hemispheric activation as the stimulus progressed while autistic population did not.
Conclusions: Both autistic and control populations showed bilaterality of language processing in initial phases of language activation. As language stimulus progressed, autistic subjects did not show suppression of right-sided activation. This may represent a mechanism for language disturbances in autism in which extraneous information is not appropriately suppressed.
The project described was supported, in part, by Grant Number RO1 MH080826 from the National Institute Of Mental Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute Of Mental Health or the National Institutes of Health.
Objectives: Determine whether increased right hemispheric processing of language results from increased right hemispheric activity or decreased left hemispheric activity relative to controls.
Methods: Twenty-five right-handed subjects (13 high-functioning autistic, 12 control) were studied using auditory and visual sentence completion tasks, and areas of differential activation between groups were identified. Hand preference was measured by Edinburgh Handedness Inventory and included as a covariable in the analysis.
Results: Autistic subjects showed significantly increased activation of right Wernicke's area compared to control subjects. After adjustment to account for differences in hand preference among groups, this difference persisted. Time series traces showed that both populations initially activated both hemispheres during the course of a language stimulus, but control population showed suppression of right-hemispheric activation as the stimulus progressed while autistic population did not.
Conclusions: Both autistic and control populations showed bilaterality of language processing in initial phases of language activation. As language stimulus progressed, autistic subjects did not show suppression of right-sided activation. This may represent a mechanism for language disturbances in autism in which extraneous information is not appropriately suppressed.
The project described was supported, in part, by Grant Number RO1 MH080826 from the National Institute Of Mental Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute Of Mental Health or the National Institutes of Health.