Exploring neural variability, movement variability and motor learning in healthy adults and people with stroke

Objective

Investigate the association between neural variability, movement variability and motor learning in people with chronic stroke and healthy adults.

Methods

Thirty participants (17 healthy, 13 stroke) underwent assessments involving transcranial magnetic stimulation and a novel pinch-grip task. Neural variability was approximated as trial-to-trial amplitude variability of motor evoked potentials recorded at the hand following transcranial magnetic stimulation to the motor cortex. Movement variability was assessed as trial-to-trial deviations when performing a pinch grip task. Motor learning was assessed on a pinch grip task to trace an unknown shape, with reward scores provided to performance.

Results

Healthy adults performed better on the motor learning task (t₍₂₈₎ = -1.70, p = 0.05). Greater movement variability was associated with better motor learning in people with stroke (r = -0.68, p = 0.015), but not healthy adults. Neural variability was not found to predict movement variability or motor learning in healthy adults or people with stroke (all p > 0.05).

Conclusion

Increased movement variability supports better motor learning in people with chronic stroke, possibly due to increased exploration of successful movement solutions.

Significance

Movement variability appears worthy of investigation to improve motor learning and recovery from stroke.