Motor skill learning is associated with diffusion characteristics of white matter in individuals with chronic stroke.
OBJECTIVE
Imaging advances allow investigation of white matter after stroke; a growing body of literature has shown links between diffusion-based measures of white matter microstructure and motor function. However, the relationship between these measures and motor skill learning has not been considered in individuals with stroke. The aim of this study was to investigate the relationships between posttraining white matter microstructural status, as indexed by diffusion tensor imaging within the ipsilesional posterior limb of the internal capsule (PLIC), and learning of a novel motor task in individuals with chronic stroke.


METHODS
A total of 13 participants with chronic stroke and 9 healthy controls practiced a visuomotor pursuit task across 5 sessions. Change in motor behavior associated with learning was indexed by comparing baseline performance with a delayed retention test. Fractional anisotropy (FA) indexed at the retention test was the primary diffusion tensor imaging-derived outcome measure.


RESULTS
In individuals with chronic stroke, we discovered an association between posttraining ipsilesional PLIC FA and the magnitude of change associated with motor learning; hierarchical multiple linear regression analyses revealed that the combination of age, time poststroke, and ipsilesional PLIC FA posttraining was associated with motor learning-related change (R = 0.649; P = 0.02). Baseline motor performance was not related to posttraining ipsilesional PLIC FA.


CONCLUSIONS
Diffusion characteristics of posttraining ipsilesional PLIC were linked to the magnitude of change in skilled motor behavior. These results imply that the microstructural properties of regional white matter indexed by diffusion behavior may be an important factor to consider when determining potential response to rehabilitation in persons with stroke.


BACKGROUND
(see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A59) for more insights from the authors.
Department of Physical Therapy (M.R.B., L.A.B.), Graduate Program in Rehabilitation Sciences (K.E.B., L.A.B.), and Brain Research Centre (L.A.B.), University of British Columbia, Vancouver, British Columbia, Canada.
Michael R
MR
Borich
Katlyn E
KE
Brown
Lara A
LA
Boyd
D000368:Aged; D016880:Anisotropy; D016022:Case-Control Studies; D002908:Chronic Disease; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D020772:Internal Capsule / Q000473:pathology*; D007858:Learning; D008297:Male; D008875:Middle Aged; D009048:Motor Skills / Q000502:physiology*; D059906:Neuroimaging / Q000379:methods*; D020127:Recovery of Function / Q000502:physiology; D020521:Stroke / Q000473:pathology*; D000071939:Stroke Rehabilitation; D066127:White Matter / Q000648:ultrastructure*