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

Abstract

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.

Keywords: Motor learning; Movement variability; Neural variability; Stroke.