Sequence-Specific Reduction of Interlimb Accuracy Asymmetry Reveals Preserved Motor Learning Dynamics in Chronic Stroke: Insights from Lesion-Aware fMRI
Background: People with chronic stroke retain the capacity to learn new motor skills, yet how preserved motor learning is expressed during practice remains incompletely understood. Sequence learning provides a useful model for examining these within-session learning dynamics and their neural basis after stroke. Objective: To characterize a temporally resolved behavioral phenotype of motor…
Background: Individuals who have experienced a stroke for an extended period still possess the ability to acquire new motor skills, yet the extent to which this preservation of motor learning manifests during practice is still unclear. Sequence learning represents an ideal model for investigating these within-session learning dynamics and their neural underpinnings following a stroke.
Objective: The goal of this study was to elucidate a detailed behavioral profile of motor sequence learning in chronic stroke patients and to determine the neural mechanisms underlying this phenomenon using task-based functional Magnetic Resonance Imaging (fMRI). Methods: A total of 24 chronic stroke patients and 14 healthy control subjects were tasked with a bimanual force-tracking sequence-learning task during functional MRI scanning.
The researchers measured performance convergence, defined as the decrease in the accuracy difference between the stronger (paretic) and weaker (less-affected) hands across practice sessions. Neural activity was examined through whole-brain, region-of-interest, and functional-connectivity analyses following a preprocessing protocol that accounted for the diverse nature of stroke lesions.
Results: Despite ongoing motor deficits, stroke patients exhibited significant performance convergence, indicating that sequence learning can still be preserved during practice. This preservation was not captured by standard behavioral assessments. Using lesion-aware fMRI, the researchers identified consistent task-related activation and maintained stage-dependent modulation within the cerebellar, premotor, and striatal regions associated with learning, as well as a reduction in bilateral putaminal activity following a stroke.
However, they did not detect any consistent associations between individual variations in performance convergence and the neural activity or functional connectivity related to learning. Conclusions: Performance convergence serves as a sensitive and temporally resolved behavioral indicator of preserved motor sequence learning in chronic stroke patients, complementing traditional endpoint measures.
The combined use of performance convergence and task-based fMRI offers a comprehensive framework for exploring individual differences in motor learning capacity and their potential impact on rehabilitation outcomes.
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