Right Hemisphere Remapping of Naming Functions Depends on Lesion Size and Location in Poststroke Aphasia.

MedStar author(s):
Citation: Neural Plasticity. 2017:8740353, 2017PMID: 28168061Institution: MedStar National Rehabilitation Network | MedStar Washington Hospital CenterDepartment: NeurologyForm of publication: Journal ArticleMedline article type(s): Journal ArticleSubject headings: *Aphasia/pa [Pathology] | *Aphasia/pp [Physiopathology] | *Cerebrum/pa [Pathology] | *Cerebrum/pp [Physiopathology] | *Neuronal Plasticity | *Stroke/co [Complications] | Aged | Aphasia/et [Etiology] | Brain Mapping | Brain/pa [Pathology] | Brain/pp [Physiopathology] | Female | Functional Laterality | Humans | Magnetic Resonance Imaging | Male | Middle AgedYear: 2017ISSN:
  • 1687-5443
Name of journal: Neural plasticityAbstract: The study of language network plasticity following left hemisphere stroke is foundational to the understanding of aphasia recovery and neural plasticity in general. Damage in different language nodes may influence whether local plasticity is possible and whether right hemisphere recruitment is beneficial. However, the relationships of both lesion size and location to patterns of remapping are poorly understood. In the context of a picture naming fMRI task, we tested whether lesion size and location relate to activity in surviving left hemisphere language nodes, as well as homotopic activity in the right hemisphere during covert name retrieval and overt name production. We found that lesion size was positively associated with greater right hemisphere activity during both phases of naming, a pattern that has frequently been suggested but has not previously been clearly demonstrated. During overt naming, lesions in the inferior frontal gyrus led to deactivation of contralateral frontal areas, while lesions in motor cortex led to increased right motor cortex activity. Furthermore, increased right motor activity related to better naming performance only when left motor cortex was lesioned, suggesting compensatory takeover of speech or language function by the homotopic node. These findings demonstrate that reorganization of language function, and the degree to which reorganization facilitates aphasia recovery, is dependent on the size and site of the lesion.All authors: Lacey EH, Skipper-Kallal LM, Turkeltaub PE, Xing SFiscal year: FY2017Digital Object Identifier: ORCID: Date added to catalog: 2017-05-06
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Journal Article MedStar Authors Catalog Article 28168061 Available 28168061

The study of language network plasticity following left hemisphere stroke is foundational to the understanding of aphasia recovery and neural plasticity in general. Damage in different language nodes may influence whether local plasticity is possible and whether right hemisphere recruitment is beneficial. However, the relationships of both lesion size and location to patterns of remapping are poorly understood. In the context of a picture naming fMRI task, we tested whether lesion size and location relate to activity in surviving left hemisphere language nodes, as well as homotopic activity in the right hemisphere during covert name retrieval and overt name production. We found that lesion size was positively associated with greater right hemisphere activity during both phases of naming, a pattern that has frequently been suggested but has not previously been clearly demonstrated. During overt naming, lesions in the inferior frontal gyrus led to deactivation of contralateral frontal areas, while lesions in motor cortex led to increased right motor cortex activity. Furthermore, increased right motor activity related to better naming performance only when left motor cortex was lesioned, suggesting compensatory takeover of speech or language function by the homotopic node. These findings demonstrate that reorganization of language function, and the degree to which reorganization facilitates aphasia recovery, is dependent on the size and site of the lesion.

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