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