Abstract
Stroke impairs connections in the brain system, commonly resulting in significant sensorimotor deficits. Some degree of functional recovery typically occurs even after a severe stroke, yet changes in the brain connectivity that underlie such recovery are poorly understood. In this study, using rat stroke models, we monitored functional connectivity when the sensorimotor deficit recovered after a severe ischemic stroke (defined DWI by more than 15% of the entire brain volume). We used seven Sprague-Dawley rats (∼350g), which showed nearly full recovery of both motor and sensory functions approximately 180 days after 90 min occlusion of the right middle cerebral artery. Six healthy age controlled rats were used for the control group. BOLD MRI time courses during rest (10min, TR=1s, 9 slices) were collected. Both the seed-voxel analysis and the ROI-based analysis were performed, in which seed voxels were selected in the left S1FL, and multiple ROIs were placed over the somatosensory regions. Stroke rats showed the markedly decreased functional connectivity in the ipsilesional side (right) for both voxelwise and ROI-based methods. Interestingly, in contralesional (non-stroke) side (left), the voxelwise connectivity spatially expanded into the entire cortical area. The cross-correlation coefficient values between ROI’s slightly increased in the contralesional hemisphere compared to the control rats. In conclusion, we demonstrated that the restoration of sensorimotor function is associated more with the increase and spatial expansion of functional connectivity within the contralesional than the ipsilesional hemisphere.
Published Version
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