Changes of Brain Connectivity in the Primary Motor Cortex After Subcortical Stroke: A Multimodal Magnetic Resonance Imaging Study

Abstract

The authors investigated the changes in connectivity networks of the bilateral primary motor cortex (M1) of subcortical stroke patients using a multimodal neuroimaging approach with antiplatelet therapy. Nineteen patients were scanned at 2 time points: before and 1 month after the treatment. The authors assessed the resting-state functional connectivity (FC) and probabilistic fiber tracking of left and right M1 of every patient, and then compared these results to the 15 healthy controls. The authors also evaluated the correlations between the neuroimaging results and clinical scores.Compared with the controls, the patients showed a significant decrease of FC in the contralateral motor cortex before treatment, and the disrupted FC was restored after treatment. The fiber tracking results in the controls indicated that the body of the corpus callosum should be the main pathway connecting the M1 and contralateral hemispheres. All patients exhibited reduced probability of structural connectivity within this pathway before treatment and which was restored after treatment. Significant correlations were also found in these patients between the connectivity results and clinical scores, which might imply that the connectivity of M1 can be used to evaluate the motor skills in stroke patients.These findings can help elucidate the neural mechanisms responsible for the brain connectivity recovery after stroke.

FIGURE 1

Group differences in the functional connectivity from left/right M1 between the stroke patients pretreatment and the controls. The significant group differences between functional connectivity of left M1 region of interest (A) and right M1 region of interest (B) on the rest of the brain. M1 = primary motor cortex.

FIGURE 2

Group comparisons of resting-state functional connectivity between groups. Bars represent the mean and error bars represent the standard deviations.

FIGURE 3

Probabilistic fiber tracking with seed in the left/right primary motor cortex. The body of the corpus callosum was the main pathway connecting the seeds to the contralateral hemisphere. The tracts in stroke patients showed a structural connectivity changed from pre- to posttreatment.