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- DOI: 10.1093/brain/awl106
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Non-invasive mapping of corticofugal fibres from multiple motor areas - relevance to stroke recovery
Newton J.M, Ward N.S, Parker GJM, Deichmann R, Alexander D.C, Friston K.J, Frackowiak R.S.J
Brain. 2006;129:1844-1858.
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Full-text held externally
- DOI: 10.1093/brain/awl106
Abstract
Recovery of motor function after subcortical stroke appears to be related to the integrity of descendingconnections from the ipsilesional cortical motor system, a view supported by the observation of greaterthan normal movement-related activation in ipsilesional motor regions in chronic subcortical stroke patients.This suggests that damage to the descending output fibres from one region of the cortical motor system may becompensated by activity in areas that retain corticofugal outputs. Though the trajectories of corticofugal fibresfrom each major component of the motor system through the corona radiata and internal capsule are welldescribed in non-human primates, they have not been described fully in humans. Our study set out to map thetrajectories of these connections in a group of healthy volunteers (8 male, 4 female; age range = 31–68 years,median = 48.5 years) and establish whether this knowledge can be used to assess stroke-induced disconnectionof the cortical motor system and better interpret functional reorganization of the cortical motor system. Wedescribe the trajectories of the connections from each major component of the motor system to the cerebralpeduncle using diffusion-weighted imaging and probabilistic tractography in normal subjects. We observedgood reproducibility of these connections over subjects. The comparative topography of these connectionsrevealed many similarities between humans and other primates. We then inferred damage to corticofugalpathways in stroke patients (n = 3) by comparing the overlap between regions of subcortical white matterdamage with the trajectories of the connections to each motor area. In a small series of case studies, we foundthat inferred disconnections could explain enhanced hand-grip-related responses, as assessed with functionalMRI, in the ipsilesional motor system. These results confirm that selective disruption of motor corticofugalfibres influences functional reorganization and outcome in individual patients.Keywords: diffusion tensor; tractography; stroke; motor recovery; functional MRI