by Stephanie Stemmler • April 5, 2021
Benjamin Philip, PhD, adjusts the video camera on an MRI-compatible tablet that can measure hand function during a brain scan.
As a brain imaging study gets underway, Benjamin Philip, PhD, watches a person in an MRI machine begin to draw on a computer tablet with their non-dominant hand.
The exercise may appear to be a simple task, but the movement is actually quite complex, sparking a series of electrical connections deep within the brain that direct the hand to move.
“I’m searching for the specific brain mechanisms that allow a person to compensate for the loss of the dominant hand and effectively use their non-dominant hand to perform tasks,” Philip says. “In other words, I’m looking for both the origin and path of electrical circuits in the brain governing hand movement.”
Philip is trying to solve a major problem: Why is it that some individuals with a peripheral nerve injury in their dominant hand are unable to compensate for that loss by effectively using their non-dominant hand? The question is at the heart of a five-year, $2.1 million National Institutes of Health R01 research grant awarded to Philip in 2020. The answer could potentially impact the rehabilitative care of more than 60,000 people diagnosed with peripheral nerve injuries in the United States.
“Is it habit?” asks Philip. “Or is it a brain connection? I think it’s going to be both.”
More than 90 percent of the world’s population is right-handed. Philip, a “lefty,” says left-handed people have learned to accommodate in this lopsided world by either using specially designed gadgets for left-handed use or by adapting to right-handed tools. “I write with my left hand, but learned to use right-handed scissors, for example. And I have a knife in my kitchen that I still sometimes mistakenly cut on the blunt side because it’s visually symmetrical unless you look at its left side, which you can only see if you’re holding it in your right hand.”
Handedness, the preference of using one hand over the other, doesn’t typically switch by choice, although a small percentage of people can be ambidextrous. And while it’s interesting to examine handedness choices for various activities in the general population, the issue becomes paramount in individuals who are upper extremity amputees or who have been diagnosed with peripheral nerve disease that prevents the use of their dominant hand.
“They can learn how to use a non-dominant hand, but it’s quite hard over the long term,” says Philip. “What I’m trying to do is identify the specific location in the brain that controls handedness and the electric circuitry where the signal travels from the brain to the arms and hands. By pinpointing this, we can use neuromodulation in addition to neurorehabilitation therapies to re-train individuals to effectively use a non-dominant hand.”
Philip’s research bridges the gap between neuroscience and occupational therapy and began after he earned his bachelor’s degree in cognitive science at Vassar College in New York. As he pursued his doctoral degree in neuroscience at Brown University, he worked with John Donoghue, PhD, a pioneering translational researcher whose team created the BrainGate brain-computer interface, designed to restore movement in people with paralysis. Philip studied the process by which the brain specifically controls hand and arm movement by implanting electrode arrays into the motor cortex of non-human primates. Within a year, as a post-doctoral fellow in the laboratory of Scott Frey, PhD, he translated his focus into human research efforts. In 2016, he became director of the Neuroscience and Rehabilitation Laboratory within the Program of Occupational Therapy at Washington University School of Medicine.
“I’ve always been interested in how the mind works and what makes it work the way that it does,” he says simply. “In the context of hand movements, despite the very best surgery and even nerve transplants or transfers, about one-third of the patients never regain their hand function to the degree that they desire. It’s those individuals that I’m trying to help.”
A major advantage for Philip is that he sits in an academic environment at Washington University that abounds with internationally renowned collaborators in neuroscience, plastic and reconstructive surgery, psychology, biostatistics and neuro-imaging. Washington University also has an internationally recognized center for nerve transplants and nerve transfers. And adjacent to the campus is the Cortex Innovation Community, a business and technology innovation hub.
Working with physician-scientists across Washington University, including Susan Mackinnon, MD, who performed the world’s first nerve transplant, Philip is also investigating whether patients purposely closing their eyes and thinking through a movement step by step will lead to faster and better rehabilitative outcomes for patients who don’t fully recover from surgical “re-wiring” alone. This process, called imagined movement, may spark a re-wiring and re-organization of brain signals that could enhance actual movement and adaptability. The research is funded by the American Society of Neurorehabilitation.
Working on a third but parallel project, Philip has added the word “inventor” to his resume. With research colleagues, he is developing a new iPad app that will measure and quantify handwriting in children. It is hoped that the app will lead to early identification of a child who may develop a writing disorder. Colleagues in Cortex are working on the business platform to bring the app to commercial use within three to five years.
At its heart, the app is a drawing game with a purpose. “It’s based on similar tools that we are using in the R01 study, but we’ve tooled it to work in a school environment on a readily available iPad using an Apple Pencil,” Philip says. Initial development of the app was funded by a Phase I Small Business Technology Transfer grant from the National Institutes of Health’s National Center for Child Health & Human Development.
In the future, Philip plans to expand his neuromodulation studies in peripheral nerve injury patients to include individuals recovering from stroke. “In both cases, we don’t know if the struggle to use a non-dominant hand is related to damage to the brain or to handedness,” he says.
He also oversees seminars and mentors MSOT, OTD and PhD students in the Program who are interested in learning more about how neuroscience serves as a foundation for therapeutic interventions. Says Philip, “I want to learn things that allow us to better understand what new therapies are possible and how we can improve what occupational therapists can do for their clients.”
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