Cortical and Biomechanical Dynamics of Ankle Robotics Training in Stroke (AbotMot)

Reduced mobility and increased fall risk are significant long-term health problems facing those who have persistent weakness or paralysis in their legs resulting from stroke. Recent innovations in post-stroke therapy have applied motor learning principles to improve motor skills through regular practice of activities using the weaker limb. Because the ankle is so critical in providing forces for normal walking and balance function, impairments at the affected ankle pose a major limitation to achieving optimal rehabilitation outcomes. To address this we have developed a novel ankle robot (Anklebot) to enhance physical therapy for improving walking and balance functions after stroke. It is a computer controlled exercise machine that can be worn during walking or in a seated position for practice with video games. The Anklebot controllers allow for assisting users when they cannot complete a movement, or resisting movement, or simply recording movements and forces.

Passive movement therapy has shown promise in exciting brain to muscle connections for recovery of walking function; however it does not appear to yield optimal results, suggesting that active involvement in task-oriented therapy is essential. Not only is voluntary movement important to initiate this excitation, the brain mechanisms of reward and motivation play an important role. These mechanisms have been widely studied in both humans and animals. Core brain networks involved in reward and motivation are designed to increase a person's involvement with their surroundings, to focus attention and to prompt one to approach reward and avoid punishers. These increases in involvement and the elevated emotions that are part of it have been shown to enhance performance, memory and learning.

The primary purpose of this pilot study is to investigate responses of brain and muscle activity in stroke patients who use the Anklebot during a 3-week / 3-session/week motor learning based training. These responses will be compared to a 3-week delayed entry period in which the participants will perform an at-home walking program equal in time spent to the time they will spend on the Anklebot during the 3-week / 3x/week training. In Addition, after the 3-week delayed entry walking program the subjects will be divided into low and high reward-feedback groups. The low reward-feedback group will receive the Anklebot training with only immediate feedback (they will know if they succeeded on the current trial but they will never know their cumulative score and they will receive minimal social interaction with research team members. While the high-reward feedback group will know their cumulative scores, will receive controlled but abundant social interaction with the research team and will be eligible for prizes of restaurant and movie coupons during individual training sessions and at completion of the study. This will be done to assess the ability of higher reward conditions to increase recovery beyond that of the Anklebot training alone.

To accomplish this subjects with chronic stroke will be divided into the high and low-reward/feedback groups and will then play a series of videogames using the Anklebot, as we noninvasively record brain activity using electroencephalography (EEG) and muscle activity using electromyography (EMG). We will also monitor heart rate using electrocardiograms (ECG). In addition to analyzing brain and muscle information before, during, and after the Anklebot training, we will also assess walking and balance functions immediately before and after the first and last robotic training session and ask the subjects to fill out some standardized questionnaires.