During a stroke, reduced blood supply to part of the brain often results in paralysis on one side of the body. If the mind ‘learns’ that a limb cannot move, paralysis then becomes a habit, even when connections from brain to limb are restored. Stroke recovery is improved with mirror box therapy, where an illusion of the paralysed limb moving is produced from the mirror-image of movement in the matching, healthy limb. How this works is not clear but scientists have started to unravel the regions of the brain involved using functional Magnetic Resonance Imaging (fMRI), which employs magnetic fields to observe changes in brain activity. Two regions, labelled A and B in the image, are activated. Both are important for self-awareness and memory, but not for muscle movement. Could mirror box therapy be helping the brain to ‘unlearn’ paralysis by making it conscious that a limb can move?
Written by Julie Webb
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.