Stroke survivors frequently show persistent gait deficits in their chronic stages even after years of intensive rehabilitation. This may be caused by diminished capability of re-acquiring motor skills post stroke. Thus, the overall purpose of this research project is to examine stroke survivors' capability of learning a novel leg task over 3 visits, 1-2 weeks apart. The capability of learning a new skill is then correlated with the individual's neurological functions (nerve activity and movement coordination) and her/his gait performance (gait speed, gait symmetry, and force production).
The walking after stroke called "hemiparetic gait" is characterized by slow and asymmetrical steps with poor motor control on the paretic leg while paradoxically increasing the cost of energy expenditure. Biomechanical evidence shows that impaired gait performance for people with chronic stroke is not solely the result of the loss of muscle strength, but involves complicated movement discoordination across multiple joints in the affected leg. This has been taken to indicate a persistent motor control deficit in the paretic leg post stroke. Recent imaging studies suggest that the persistent motor control deficit after stroke may be the result of the disruption of motor memory consolidation, a process by which a newly-learned motor skill is transformed from a fragile state to a stable state and is "saved" in our brain afterward. This indicates that the same brain area responsible for controlling motor activity is also involved in memorizing newly-learned skills during the early stage of motor learning. Presence of persistent motor control deficits in the chronic stage may be attributed to the fact that damage to the brain cortex significantly impacts the ability of acquiring motor skills and consequentially defers the improvement of motor function, including gait.
Study Type
OBSERVATIONAL
Enrollment
130
Similar to a hand reaching task in which participants were asked to reach to a tea-cup, in a visuomotor leg reaching task, participants will be seated and given real-time visual feedback about their leg movements via a cursor display on a computer screen. The task is to control a foot mouse/marker attached to the foot and move the cursor from a start location to the target displayed on a wall screen. Three different targets, equidistant from the start location at top, top-left, and top-right screen positions, will be used for leg reaching. In each trial, one of three targets will be randomly presented and subjects will be instructed to make forward, or rightward, or leftward foot reaches to guide the cursor to one of the targets. Throughout the entire experiment, subjects are blocked from viewing leg movements by a cardboard.
Texas Woman's University
Houston, Texas, United States
RECRUITINGChanges in movement errors
Average movement error will be calculated as the angular deviation of the foot path from a straight line path to the target at the time of peak velocity in each trial.
Time frame: During the first session of learning visuomotor leg reaching task, 24-hour after the first session, and 7-days after the first learning learning session
Peripheral nerve activity
A surface electrode will be placed on the calf muscle in one leg. Then a low-intensity of electrical stimulation will be delivered to a nerve behind the knee to trigger the motor responses.
Time frame: During the first session of learning visuomotor leg reaching task
Walking performance
Gait speed will be calculated during overground walking
Time frame: Before the first session of learning visuomotor leg reaching task
Mini-mental State Examination
A standardized questionnaires to evaluate the cognitive function consisting of 11 items with a possible summed score ranging from zero to 30. The most widely accepted and frequently used cutoff score for the MMSE is 23, with scores of 23 or lower indicating the presence of cognitive impairment. A higher score means a better cognitive function.
Time frame: Before the first session of learning visuomotor leg reaching task
Fugl-Meyer Lower Extremity Function Assessment
A standardized questionnaires to evaluate the lower extremity motor function consisting of movement, coordination, and reflex assessments at hip, knee, and ankle. Possible summed scores range from zero to 34. Higher scores indicate higher and better motor function.
Time frame: Before the first session of learning visuomotor leg reaching task
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