Error AugmentationThe Role of Cognition in Motor Learning After Stroke

Stroke leads to lasting problems in using the upper limb (UL) for everyday life activities. While rehabilitation programs depend on motor learning, UL recovery is less than ideal. Implicit learning is thought to lead to better outcomes than explicit learning. Cognitive factors (e.g., memory, attention, perception), essential to implicit motor learning, are often impaired in people with stroke. The objective of this study is to investigate the role of cognitive deficits on implicit motor learning in people with stroke. The investigators hypothesize that 1) subjects with stroke will achieve better motor learning when training with additional intrinsic feedback compared to those who train without additional intrinsic feedback, and 2) individuals with stroke who have cognitive deficits will have impairments in their ability to use feedback to learn a motor skill compared to individuals with stroke who do not have cognitive deficits.

A recent feedback modality, called error augmentation (EA), can be used to enhance motor learning by providing subjects with magnified motor errors that the nervous system can use to adapt performance. The investigators will use a custom-made training program that includes EA feedback in a virtual reality (VR) environment in which the range of the UL movement is related to the patient's specific deficit in the production of active elbow extension. An avatar depiction of the arm will include a 15 deg elbow flexion error to encourage subjects to increase elbow extension beyond the current limitations. Thus, the subject will receive feedback that the elbow has extended less than it actually has and will compensate by extending the elbow further. Subjects will train for 30 minutes with the EA program 3 times a week for 9 weeks. Kinematic and clinical measures will be recorded before, after 3 weeks, after 6 weeks, and after 9 weeks. Four weeks after the end of training, there will be a follow-up evaluation. Imaging scans will be done to determine lesion size and extent, and descending tract integrity with diffusion tensor imaging (DTI).

This study will identify if subjects with cognitive deficits benefit from individualized training programs using enhanced intrinsic feedback. The development of treatments based on mechanisms of motor learning can move rehabilitation therapy in a promising direction by allowing therapists to design more effective interventions for people with problems using their upper limb following a stroke.