Making a mental match: Pairing a mechanical device with stroke patients (w/ Video)

A pneumatic actuator tendon hammer hits a person's wrist while a transcranial magnetic stimulator creates a weak signal in the brain's motor cortex. The responses overlap in the brain, produce and send a strong signal back to the arm, and the wrist moves. Credit: Georgia Tech

The repetitive facilitation exercise (RFE) is one of the most common rehabilitation tactics for stroke patients attempting to regain wrist movement. Stroke hemiparesis individuals are not able to move that part of their body because they cannot create a strong enough neural signal that travels from the brain to the wrist.

With RFE, however, patients get a mental boost. They are asked to think about moving. At the same time, a practitioner flexes the wrist. The goal is to send a long latency response from the stretch that arrives in the brain at the exact time the thought happens, creating a . The result is a strong, combined response that zips back to the forearm muscles and moves the wrist.

It all happens in a span of approximately 40 to 60 milliseconds.

"Timing is everything. When the window is that small, it's not easy for two people to match each other," said Georgia Institute of Technology master's graduate Lauren Lacey.

That's why Lacey and a team of fellow Georgia Tech researchers created mechanical device that takes people out of the process, replacing them with accurate computers. Their functional MRI-compatible hemiparesis rehab device creates a long latency stretch reflex at the exact time as a .

"It's kind of like trying to fill a bucket with water," explained Minoru Shinohara, an associate professor in Georgia Tech's Human Neuromuscular Physiology Lab. "Stroke individuals can only mentally fill it halfway. The machine pours in the rest to make it full."

Making a mental match: Pairing a mechanical device with stroke patients
The Georgia Tech device tabs a person's wrist while a transcranial magnetic stimulator creates a signal in the brain. Credit: Georgia Tech

So far, the research team has worked only with healthy individuals in their study. Study participants lie on a bed with the arm extended beneath a pneumatic actuator tendon hammer. In order to simulate the weak signal created by hemiparesis individuals to move their wrist, a transcranial magnetic stimulator (TMS) is placed on the heads of these healthy individuals at a 45-degree angle. Milliseconds after the hammer taps the wrist's tendon, the TMS creates a weak signal in the motor cortex. The responses overlap, produce and send a strong signal back to the arm, and the moves.

The team has successfully varied the timing of the TMS signal and speed of the hammer to strike faster or slower depending on how much of a boost is needed to complement the brain signal. Now that the researchers have proven the viability of the TMS-actuator system, they will next work with stroke individuals.

"The device is designed to adapt to people whether they are hyper, normo or hyporeflexive," said Lacey, who graduated in spring with a master's degree from the George Woodruff School of Mechanical Engineering.

This video is not supported by your browser at this time.

Also, because the machine is MRI-compatible, it will allow the team to study what is happening in the brain during rehab, opening the door for robotics.

"Once we fully understand what is happening mentally and physiologically, we should be able to create a robot that can reproduce successful rehabilitative exercises such as RFE," said Jun Ueda, an associate professor in the School of Mechanical Engineering. "It appears that the timing is the critical piece of this exercise. Robots are great at timing, so the results are very promising for robotics."

add to favorites email to friend print save as pdf

Related Stories

Watching individual neurons respond to magnetic therapy

Jun 29, 2014

Engineers and neuroscientists at Duke University have developed a method to measure the response of an individual neuron to transcranial magnetic stimulation (TMS) of the brain. The advance will help researchers ...

New research on stroke aims to help recovery

Jun 20, 2014

Stroke is the leading cause of adult disability worldwide but new funding of $1.2 million for research at the University of Auckland aims to better help people recover normal movement after stroke.

Human arm sensors make robot smarter (w/ Video)

Jan 16, 2014

Using arm sensors that can "read" a person's muscle movements, Georgia Institute of Technology researchers have created a control system that makes robots more intelligent. The sensors send information to ...

Recommended for you

'Chatty' cells help build the brain

15 hours ago

The cerebral cortex, which controls higher processes such as perception, thought and cognition, is the most complex structure in the mammalian central nervous system. Although much is known about the intricate ...

'Trigger' for stress processes discovered in the brain

Nov 27, 2014

At the Center for Brain Research at the MedUni Vienna an important factor for stress has been identified in collaboration with the Karolinska Institutet in Stockholm (Sweden). This is the protein secretagogin ...

New research supporting stroke rehabilitation

Nov 26, 2014

Using world-leading research methods, the team of Dr David Wright and Prof Paul Holmes, working with Dr Jacqueline Williams from the Victoria University in Melbourne, studied activity in an area of the brain ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.