Imaging Laterality in Chronic Stroke Patients

All participants will receive a comprehensive clinical assessment of motor function including the Rasch modified version of the Fugl-Meyer Motor assessment and a kinematic assessment of unimanual and bimanual movements using a 45 sensor 3D active marker based motion capture system. The three primary measures investigated in the kinematics include: 1) movement efficiency, 2) movement smoothness, and 3) motor compensation.

High-resolution structural scans will be obtained using an inversion recovery 3D spoiled gradient echo (3DSPGR) sequence using a matrix size of 256 x 256, field of view of 24 cm, section thickness of 1.5 mm with no gap between sections, and 128 slices, giving an in-plane resolution of 0.94 mm. This sequence will be used for anatomic overlays of the functional data and for spatial normalization to a standard atlas.

Briefly, patients will be given two pressure-sensitive bulbs (one to be held in each hand and fastened lightly to their wrists with Velcro such that they do not drop it during the scan. During two 2½ minute runs they will be prompted to squeeze the bulb in either their affected or unaffected hand in blocks of 15 seconds. These blocks will be interspersed with blocks of rest. The pressure from the bulbs will be digitally recorded and quantified offline in order to: 1) verify that the patient was squeezing the ball, and 2) assess the presence of 'mirror movements' from the opposing hand that may inform the imaging results regarding loss of laterality).