Learning, Not Adaptation, Characterizes Stroke Motor Recovery: Evidence From Kinematic Changes Induced by Robot-Assisted Therapy in Trained and Untrained Task in the Same Workspace

Abstract

Both the American Heart Association and the VA/DoD endorse upper-extremity robot-mediated rehabilitation therapy for stroke care. However, we do not know yet how to optimize therapy for a particular patient’s needs. Here, we explore whether we must train patients for each functional task that they must perform during their activities of daily living or alternatively capacitate patients to perform a class of tasks and have therapists assist them later in translating the observed gains into activities of daily living. The former implies that motor adaptation is a better model for motor recovery. The latter implies that motor learning (which allows for generalization) is a better model for motor recovery. We quantified trained and untrained movements performed by 158 recovering stroke patients via 13 metrics, including movement smoothness and submovements. Improvements were observed both in trained and untrained movements suggesting that generalization occurred. Our findings suggest that, as motor recovery progresses, an internal representation of the task is rebuilt by the brain in a process that better resembles motor learning than motor adaptation. Our findings highlight possible improvements for therapeutic algorithms design, suggesting sparse-activity-set training should suffice over exhaustive sets of task specific training.

Submovements during reaching movements after stroke

“…5,9 Interestingly, it has been hypothesized that submovements are the "building blocks" of movements, that is, during motor learning submovements blend as the movements become smooth and more accurate when the task begins to be mastered. 7,10 Here we report differences in the amount and type of submovements in two groups of SS with differing levels of motor impairment performing reaching movements. Most studies on motor function after stroke, whether small or largescale, consist of heterogeneous groups of SS (e.g.…”

Effects of newly developed compact robot-aided upper extremity training system (Neuro-X®) in patients with stroke: A pilot study

“…The functional recovery mechanism of the upper extremity induced by the Neuro-X® used in this study is likely to be associated with motor learning, motor adaptation, and compensation among various recovery mechanisms of the brain (32,33). In general, recovery of the brain function is known to be achieved by repeated exercise training with high intensity.…”

The generalization of motor recovery after stroke: Assessment within and outside the training workspace

“…Therapists cannot possibly train all the challenging tasks a patient will face after rehabilitation discharge. Therefore, facilitating transfer of strategies from trained to non-trained (but related) tasks would be very important for the clinical success of a therapy programme [9]. The goal of the present study was to verify the occurrence of transfer of motor skills from trained to non trained tasks in chronic stroke patients who were trained on pointto-point movements with the assistance of a rehabilitation robot.…”

“…diamond-shaped) path. To this end, the segments of the diamond-shaped path were subdivided into: those "Within" the trained workspace (Fig 1. Panel B, segments 7, 10, 13, 16) and those "Outside" the trained workspace (Fig 1. Panel B segments 5,6,8,9,11,12,14,15). In particular we compared:…”