Stimulating the Mind for Neurorehabilitation

Exploring the mechanisms that lead to relearning of motor functions following brain injury or stroke

by Stephanie Stemmler • April 14, 2023

Johnson uses a mobile arm support to aid in the completion of the Action Research Arm Test (ARAT).

Brian Johnson, OTR/L, PhD, assistant professor in the Program in Occupational Therapy and in the Department of Neurology at Washington University School of Medicine, wants to see if neuromodulatory interventions such as electrical stimulation can “ramp up” the brain’s ability to retain and then use certain motor functions.

In his new Neurorehabilitation and Applied Physiology Laboratory, Johnson is exploring the mechanisms that lead not only to the relearning of motor functions after a brain injury or stroke, but also to long-term retention of those skills.

“When you ask some patients during rehabilitation whether they’ve done their daily exercises after leaving therapy, a lot of times, the answer is ‘no,’” says Johnson. “Seeing a person one to three times a week, then, only has so much benefit. I’m interested in how we can tap into the more significant time periods that are away from a therapist to improve rehabilitation outcomes.”

Johnson has been working with stroke and spinal cord injury patients since he started as an occupational therapist in Madison, Wis. But as he provided intense rehabilitation and watched his patient improve, he wanted to know more about basic mechanisms that guide learning and neurodevelopment in motor skill rehabilitation. He switched career paths to work as a rehabilitation scientist, first in the Department of Physical Therapy and Rehabilitation Science at the University of Maryland School of Medicine, and then in the Human Cortical Physiology and Neurorehabilitation Section at the National Institutes of Health (NIH). He was there in 2019 while groups of researchers were exploring what the brain does during periods of rest after learning a motor skill. The NIH research, which is still underway, led to a published study in Cell Reports in 2021 that showed that the brain replays a new skill memory over and over during short, frequent breaks as a person learns and then practices a new skill. In other words, rest, coupled with frequent practice, strengthened skill development.

Johnson wanted to take his research in a new direction. What if you could selectively target certain memories and enhance rehabilitation by using electrical or magnetic stimulation or even auditory triggers while someone is sleeping to reinforce relearned motor skills after a brain injury?

“For my doctoral dissertation, I paired a novel auditory tone with a specific activity,” says Johnson. “After hundreds of repetitions, participants associated the sound with doing a particular exercise. Then, I would silently replay those sounds while participants slept and monitored their brain activity.”

As Johnson reviewed brain activity, he could see that the auditory cue had an effect similar to that seen in the classic response studies achieved by Ivan Pavlov, who found that dogs salivated when they associated a specific activity or person with food. In Johnson’s studies, he saw that auditory cues could make participants better at learning and retaining a motor skill even while sleeping.

He was drawn to Washington University’s Program in Occupational Therapy because of the invigorating environment for both clinical and translational research. In his lab, he will study electrical stimulation to see if targeting certain circuits of the brain can further influence how it consolidates motor skill memory. Transcranial magnetic stimulation, which also can be directed at specific areas of the brain, also will be studied. “We can pair sounds during therapy and then have a patient go home with a sound machine to use at night,” Johnson says. “With electrical stimulation, we can use a very light electrical current to influence specific brain areas during therapy and then send patients home with a device similar to a portable TENS (transcutaneous electrical nerve stimulation) device.”

Along with transcranial magnetic stimulation, which delivers repetitive magnetic pulses, the therapy already is being used to treat depression. Johnson wants to see if it can be used to influence relearning of motor skills.

Yin and Yang

In addition to his background as a practicing occupational therapist and researcher, Johnson has been a member of the U.S. Army Reserve since 2020. In the Army, he says, occupational therapists have a unique role in the delivery of mental health services and rehabilitation for military personnel experiencing post-traumatic stress disorder (PTSD) or struggling with coping mechanisms.

“The clinical work I do in the Army lets me think of things that are clinically relevant, and I can bring that back to my research in the lab,” he says. “And vice versa, through the research that I’m conducting, I can ultimately bring that to the clinical realm. So my roles here in the Program and in the Army are like yin and yang to me.”

In the Army Reserve, Johnson serves in the Combat and Operational Stress Control (COSC) program, based in Wisconsin. COSC’s mission is to prevent, proactively identify, and mitigate stressors to enhance long-term health and well-being among servicemembers.

“We want individuals to be independent in what they want or have to do,” Johnson explains. “Same as in occupational therapy, where our focus is on improving function and aspects of daily living, we focus on coping mechanisms and the learning and retention of specific skills.”

In addition to his time in the Army Reserve, Johnson maintains a connection to the NIH through his affiliation with the Special Volunteer Scientist program. At Washington University, Johnson will be conducting sleep studies to evaluate neuromodulatory interventions. He is in the process of looking for a research coordinator and will be mentoring three occupational therapy doctoral students this summer, who will be conducting research in his lab.

“I have an ambitious goal to change how rehabilitation is designed and scheduled,” says Johnson. “Active and passive learning is key to that, and I want to help patients fully capitalize on their time during a therapy session and in between the sessions when we know that learning is still occurring.”

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