movement velocity effect on cortical reorganization and finger function in stroke

Conditions: Stroke

Summary: aim 1. determine whether higher-velocity finger tracking training improves hand function more than slower velocity training. working hypotheses: the higher-velocity training will have significantly greater functional improvement compared to the lower-velocity training, as measured by standardized upper extremity functional tests (jebsen taylor test, box \& block test, and finger extension force test) aim 2. ascertain whether higher-velocity finger tracking training differentially induces cortical reorganization as compared to lower-velocity finger tracking training. working hypotheses: the higher-velocity training will have significantly greater cortical reorganization compared to the lower-velocity training, as measured by: 1. tms - increased amplitude of motor evoked potentials (mep) from paretic extensor digitorum muscle in response to paired-pulse tms to ipsilesional primary motor area (m1). 2. fmri - increased volume of activation, signal intensity, and laterality of ipsilesional m1. aim 3. explore whether the functional improvements correlate with the cortical reorganization. working hypotheses: the functional improvements will correlate with the cortical reorganization.


Eligibility criteria:
inclusion criteria include: * ischemic stroke - due to higher risk of seizures in hemorrhagic stroke * subcortical location of stroke * stroke after 6 months - lower limit of 6 months to avoid confounding from spontaneous recovery (jorgensen, nakayama et al. 1995) and no upper limit to maximize pool of candidate subjects while still showing training effect (carey, kimberley et al. 2002) * at least 18 years of age - to maximize pool of candidate subjects * mini-mental state examination score \>24 - to ensure satisfactory cognition to perform tasks * satisfactory corrected vision - to see computer screen during training and testing * active range of mp joint at paretic index finger of at least 10 degrees - based on minimal movement required to perform training task successfully, and that larger amplitudes would reduce the pool of subjects available for participating in the study. * ability to pronate the forearm so that index finger extension movement during training is vertically upward and relaxation results in the finger falling back to the flexed starting position * not currently receiving any other therapy - to avoid confounding treatment effects * approval for participation by a neurologist - to ensure subject is reasonably safe to receive tms testing. subjects with proprioceptive loss or expressive aphasia will be included, providing they can carryout the training task. exclusion criteria include: * inability to follow 3-step commands * a visual field cut that causes subjects not to see all indicators on a computer screen positioned centrally in from of them * history of seizures * family member with history of seizures * presence of any other neuromuscular disorders * pregnancy * claustrophobia * indwelling metal or medical devices/implants incompatible with functional fmri testing * history of exposure to finger tracking training. * informed consent will be obtained and tms/fmri safety screenings will be conducted prior to testing procedures. * subjects will be recruited as volunteers from letters sent to previous research subjects inviting their participation, through visits to local stroke support groups meetings, newspaper advertisements and referrals from neurologists.