November 21, 2011
Regeneration After A Stroke Requires Intact Communication Channels Between The Two Halves Of The Brain
Recovery depends on the exchange of information between the brain hemispheres
The structure of the corpus callosum, a thick band of nerve fibres that connects the two halves of the brain with each other and in this way enables the rapid exchange of information between the left and right hemispheres, plays an important role in the regaining of motor skills following a stroke. A study currently published in the journal Human Brain Mapping has shown that in stroke patients with particularly severely impaired hand movement, this communication channel between the two brain hemispheres in particular was badly damaged.
In order to demonstrate the structural connection between brain areas, the Cologne researchers used diffusion-based magnetic resonance imaging (dMRI), which can be used to reconstruct longer stretches of nerve fibres. dMRI is based on the principle that cell elements, such as the membrane or extensions, inhibit the spread of water molecules thereby preventing them from diffusing randomly in all directions. Consequently, parallel nerve fibres can be clearly identified using dMRI. Compared to the healthy control group, the stroke patients had lower diffusion values in the corpus callosum region. This would indicate that this interhemispheric communications connection was damaged by the stroke. The most significant deviations from the values of the control group were observed in patients with more severe motor defects and increased activity in the healthy brain hemisphere.
Therefore, in addition to cell death in the actual stroke area, damage to a very distant connection structure plays a crucial role in the inability of stroke patients to fully regain their original motor capacities. “This is why, we are currently examining whether we can regenerate the communication between the brain hemispheres through early and regular stimulation treatment. Our long-term aim is to improve motor deficits in stroke patients,” says Grefkes.
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