Increased reward in ankle robotics training enhances motor control and cortical efficiency in stroke

Robotics is rapidly emerging as a viable approach to enhance motor recovery after disabling stroke. Current princi- ples of cognitive motor learning recognize a positive relationship between reward and motor learning. Yet no prior studies have established explicitly whether reward improves the rate or effi- cacy of robotics-assisted rehabilitation or produces neurophysio- logic adaptations associated with motor learning. We conducted a 3 wk, 9-session clinical pilot with 10 people with chronic hemiparetic stroke, randomly assigned to train with an imped- ance-controlled ankle robot (anklebot) under either high reward (HR) or low reward conditions. The 1 h training sessions entailed playing a seated video game by moving the paretic ankle to hit moving onscreen targets with the anklebot only pro- viding assistance as needed. Assessments included paretic ankle motor control, learning curves, electroencephalograpy (EEG) coherence and spectral power during unassisted trials, and gait function. While both groups exhibited changes in EEG, the HR group had faster learning curves (p = 0.05), smoother move- ments (p motor learning for restoring mobility. Clinical Trial Registration: ClinicalTrials.gov; NCT01072032; "Cortical and biomechanical dynamics of ankle robotics training in stroke"; http://www.clinicaltrials.gov/ct2/show/NCT01072032