title: Atypical right hemisphere specialization for object representations in an adolescent with specific language impairment.
abstract: Individuals with a diagnosis of specific language impairment (SLI) show abnormal spoken language occurring alongside normal non-verbal abilities. Behaviorally, people with SLI exhibit diverse profiles of impairment involving phonological, grammatical, syntactic, and semantic aspects of language. In this study, we used a multimodal neuroimaging technique called anatomically constrained magnetoencephalography (aMEG) to measure the dynamic functional brain organization of an adolescent with SLI. Using single-subject statistical maps of cortical activity, we compared this patient to a sibling and to a cohort of typically developing subjects during the performance of tasks designed to evoke semantic representations of concrete objects. Localized patterns of brain activity within the language impaired patient showed marked differences from the typical functional organization, with significant engagement of right hemisphere heteromodal cortical regions generally homotopic to the left hemisphere areas that usually show the greatest activity for such tasks. Functional neuroanatomical differences were evident at early sensoriperceptual processing stages and continued through later cognitive stages, observed specifically at latencies typically associated with semantic encoding operations. Our findings show with real-time temporal specificity evidence for an atypical right hemisphere specialization for the representation of concrete entities, independent of verbal motor demands. More broadly, our results demonstrate the feasibility and potential utility of using aMEG to characterize individual patient differences in the dynamic functional organization of the brain.
authors.affiliation: Multimodal Imaging Laboratory, University of California San Diego , La Jolla, CA , USA ; Department of Neurosciences, School of Medicine, University of California San Diego , La Jolla, CA , USA ; Center for Human Development, University of California San Diego , La Jolla, CA , USA.
authors.forename: Timothy T
authors.initials: TT
authors.lastname: Brown
authors.affiliation: Multimodal Imaging Laboratory, University of California San Diego , La Jolla, CA , USA ; Department of Radiology, School of Medicine, University of California San Diego , La Jolla, CA , USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Erhart
authors.affiliation: Program in Experimental and Molecular Medicine, Dartmouth Medical School , Hanover, NH , USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Avesar
authors.affiliation: Multimodal Imaging Laboratory, University of California San Diego , La Jolla, CA , USA ; Department of Neurosciences, School of Medicine, University of California San Diego , La Jolla, CA , USA ; Department of Radiology, School of Medicine, University of California San Diego , La Jolla, CA , USA.
authors.forename: Anders M
authors.initials: AM
authors.lastname: Dale
authors.affiliation: Multimodal Imaging Laboratory, University of California San Diego , La Jolla, CA , USA ; Department of Neurosciences, School of Medicine, University of California San Diego , La Jolla, CA , USA ; Department of Radiology, School of Medicine, University of California San Diego , La Jolla, CA , USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Halgren
authors.affiliation: Center for Research in Language, University of California San Diego , La Jolla, CA , USA ; School of Behavioral and Brain Sciences, University of Texas Dallas , Dallas, TX , USA.
authors.forename: Julia L
authors.initials: JL
authors.lastname: Evans
keywords: cerebral dominance; hemispheric specialization; magnetoencephalography; object concepts; semantic representations; specific language impairment