The idea came up over lunch. Howard Chizeck, co-director of the UW Biorobotics Lab, was brainstorming with neurosurgeon Jeff Ojemann and several others about treating tremors by electrically stimulating the brain. They started cooking up plans to improve existing technology. “We literally drew it out on a napkin,” says Chizeck.
Now, a few years later, their sketched-out conversation is a full-fledged study—one with human participants who are using their brains’ own signals to control a tremor-reducing device implanted deep inside their heads. This innovative project is the kind of inspired collaboration at the core of the UW’s Center for Sensorimotor Neural Engineering.
Established in 2011 and funded by the National Science Foundation, the CSNE specializes in brain-computer research and supports such projects as reanimating limbs and helping the brain compensate for injury and disease. Based at the UW and working with partners at MIT and San Diego State University, the research center brings together engineers, medical specialists, neuroscientists, statisticians, psychologists and ethicists.
Essential tremor, the most common movement disorder, affects about 7 million Americans. This nervous-system condition presents as a rhythmic shaking, particularly when a person is trying to perform a task. Efforts like holding a water glass, writing and eating can be difficult. The cause is unknown and the tremor worsens over time.
Most of the time, this disorder is treated with drugs. But medication affects people in different ways, says Chizeck. For some, the drugs don’t work at all. These patients are candidates for deep brain stimulation, which involves surgically implanting electrodes into the brain. An electrical pulse quells the tremor. But for a variety of reasons, this technology is not ideal, says Chizeck. In its current form, the stimulator runs all the time, which shortens the life of its battery. There are times when a person may not need the stimulation, and there are side effects, which range from inhibiting speech to causing tingling in extremities.
Doctors and scientists are still puzzling out why deep brain stimulation works. The FDA approved the idea of planting electrodes in the brain to treat issues like Parkinson’s disease and essential tremor in 2002. Portable batteries and biocompatible materials have made it easier to do. Today, about 200,000 people have clinically-approved implants suppressing their tremors.
“The project is paving the way for new cutting-edge neurotechnologies being developed at the center that will improve the quality of life of individuals with stroke, spinal cord injury and other neurological conditions.”
Rajesh Rao, co-director of the Center for Sensorimotor Neural Engineering
The CSNE team, which includes UW neurosurgeon Andrew Ko, is using a stimulator produced by Minneapolis-based Medtronic, in which a device similar to a pacemaker is implanted beneath the collarbone. Connective wires run up the neck and the back of the head and into the brain to the electrodes. Using a stimulator all the time might not be necessary, says Maggie Thompson, an electrical engineering Ph.D. student working with patients in this trial. The tremors and their challenges may be less of an issue at different times of day, she says. When a person is sleeping, for example, he or she experiences fewer tremors. That the battery has to be surgically replaced every three to five years is also a concern. So Chizeck’s team set about creating a closed-loop system that could be turned on and off using signals from a person’s own brain.
During the surgery to implant the deep brain electrodes, Ko places another set of electrodes on top of the brain to read and communicate tremors and impending movement to the deep brain device. The signals from the second set of electrodes turn on the electrical stimulation to stop the tremors. Not only does the closed-loop system respond to the patient’s own activity, it also collects data for the researchers. “We’ve got kind of a new microscope into the brain,” says Chizeck. Over time, the data they collect will help the team understand how the brain adapts to the technology.
While Thompson and student colleagues Ben Ferleger, Andrew Haddock and recent Ph.D. Brady Houston are working with patients, studying them as they perform particular physical tasks, their lab mate, Timothy Brown, asks a series of questions about how they’re responding to the device. “I’m interested in what happens if you cause a change to something that serves your identity and your locus of control,” says Brown, a philosophy graduate student who studies the ethics of neural technology. He explores the moral questions around whether having a computer inside a person changes their identity and agency. “We wanted to address the ethics of using this technology up front, not as Band-Aids later on,” says Chizeck, adding that a neuro-ethics focus is central to the work done through the center.
Other members of the project—which is funded by Medtronic, the National Science Foundation and the center—are helping refine the stimulation pattern and improve the software and algorithms to be more responsive to the patient. They have found that the closed-loop system seems to work better, gives the batteries longer life, reduces tremor, offers users better control in their hands and has fewer side effects.
“The essential tremor project is a perfect example of how the CSNE is catalyzing path-breaking interdisciplinary research at the UW,” says Rajesh Rao, co-director of the CSNE. “The project is paving the way for new cutting-edge neurotechnologies being developed at the center that will improve the quality of life of individuals with stroke, spinal cord injury and other neurological conditions.”