Archer et al. - 2016 - Microstructural Properties of Premotor Pathways Predict Visuomotor Performance in Chronic Stroke - Unknown.pdf

Microstructural properties of the corticospinal tract (CST) descending from the motor cortex predict
strength and motor skill in the chronic phase after stroke. Much less is known about the relation
between brain microstructure and visuomotor processing after stroke. In this study, individual’s
poststroke and age-matched controls performed a unimanual force task separately with each hand at three
levels of visual gain. We collected diffusion MRI data and used probabilistic tractography algorithms to
identify the primary and premotor CSTs. Fractional anisotropy (FA) within each tract was used to predict
changes in force variability across different levels of visual gain. Our observations revealed that individuals
poststroke reduced force variability with an increase in visual gain, performed the force task with
greater variability as compared with controls across all gain levels, and had lower FA in the primary
motor and premotor CSTs. Our results also demonstrated that the CST descending from the premotor cortex,
rather than the primary motor cortex, best predicted force variability. Together, these findings demonstrate
that the microstructural properties of the premotor CST predict visual gain-related changes in force
variability in individuals poststroke