A diffusion spectrum imaging study of the cortico-subcortical motor connections after stroke

Connectivity plasticity in the uninjured hemisphere after stroke has been reported in a number of experimental [1-2] and human [3-5] studies. Recently, we used Diffusion Spectrum Imaging (DSI) to explore longitudinal changes in the contra-lateral motor network of patients, who suffered from stroke and had good functional recovery [6]. In this study, we showed a broad spectrum of changes in Generalized Fractional Anisotropy (GFA) in connections between primary and secondary motor areas contralateral to the injured hemisphere [6]. Furthermore, GFA measured in the acute phase together with a routine motor score and age proved to be strong predictors of motor outcome at six months (r2=0.96, p=0.0002) [6]. In the current work, we aimed at investigating the presence of remodelling of the cortico-subcortical motor system (CS-MS) in the same cohort of stroke patients. The CS-MS is constituted by connections between the cortical motor area and the basal ganglia and the thalamus and is essentially constituted by three major subcortical network (figure 1A): i) the sensory-motor sub-loop (primary and sensory motor areas, - putamen-globus pallidus - ventral lateral thalamic nucleus-motor cortex), ii) the premotor sub-loop ( premotor dorsal and ventral areas (dPM, vPM)-caudate nucleus - putamen, -globus pallidus - - ventral anterior thalamic nuleus-premotor cortex iii) the supplementary motor area (SMA) sub-loop (SMA - putamen and caudate- globus pallidus -ventral anterior and the ventro-lateral thalamic nuclei-SMA).