The coordination of bimanual prehension movements in a centrally deafferented patient

Many everyday tasks require that we use our hands cooperatively, for exampl e, when unscrewing a jar. For tasks where both hands are required to perfor m the same action, a common motor programme can be used. However, where eac h hand needs to perform a different action, some degree of independent cont rol of each hand is required. We examined the coordination of bimanual move ment kinematics in a female patient recovering from a cerebrovascular accid ent involving anterior regions of the parietal lobe of the right hemisphere , which resulted in a dense hemianaesthesia of her left arm. Our results in dicate that unimanual movements executed by our patient using her non sensa te hand are relatively unimpaired, In contrast, during bimanual movements, reaches executed by our patient using her non-sensate hand show gross direc tional errors and spatiotemporal irregularities, including the inappropriat e coupling of movement velocities. These data are discussed with reference to the role played by limb proprioception in the planning and control of pr ehension movements.