1. Impact of 5-Hz rTMS over the primary sensory cortex is related to white matter volume in individuals with chronic stroke.
- Author
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Brodie, Sonia M., Borich, Michael R., and Boyd, Lara A.
- Subjects
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WHITE matter (Nerve tissue) , *SENSORY neurons , *TRANSCRANIAL magnetic stimulation , *BRAIN stimulation , *MOTOR learning , *SOMATOSENSORY cortex , *PREDICTION theory - Abstract
Repetitive transcranial magnetic stimulation ( rTMS) is a non-invasive brain stimulation technique that may facilitate mechanisms of motor learning. In a recent single-blind, pseudo-randomized study, we showed that 5-Hz rTMS over ipsilesional primary somatosensory cortex followed by practice of a skilled motor task enhanced motor learning compared with sham rTMS + practice in individuals with chronic stroke. However, the beneficial effect of stimulation was inconsistent. The current study examined how differences in sensorimotor cortex morphology might predict rTMS-related improvements in motor learning in these individuals. High-resolution T1-weighted magnetic resonance images were acquired and processed in FreeSurfer using a newly developed automated, whole brain parcellation technique. Gray matter and white matter volumes of the ipsilesional primary somatosensory and motor cortices were extracted. A significant positive association was observed between the volume of white matter in the primary somatosensory cortex and motor learning-related change, exclusively in the group that received active 5-Hz rTMS. A regression model with age, gray matter and white matter volumes as predictors was significant for predicting motor learning-related change in individuals who received active TMS. White matter volume predicted the greatest amount of variance (47.6%). The same model was non-significant when volumes of the primary motor cortex were considered. We conclude that white matter volume in the cortex underlying the TMS coil may be a novel predictor for behavioral response to 5-Hz rTMS over the ipsilesional primary somatosensory followed by motor practice. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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