How Brain-machine Interfaces are Helping Paralyzed Limbs Move

Miller to discuss pathbreaking research at October 24 Science Café event

By Roger AndersonOctober 15, 2018

Before any conversation about his research begins, Northwestern neuroscientist Lee Miller can already anticipate the big question.

If he can restore arm movement in a paralyzed monkey, when might he be able to do the same in humans?

The answer — which Miller will discuss at this month’s Science Café event — is “sooner than you may think.”

“Scientists are on the cusp of making this a reality,” says Miller, a 2016 inductee into the American Institute for Medical and Biological Engineering’s College of Fellows. “With technological advances and an increased funding focus, the idea of solving spinal cord injuries with an electronic device will likely happen in the next five or 10 years.”’

Humans with spinal cord injury lack the connections between brain and spinal cord circuits that are essential for voluntary movement. Worldwide, more than 130,000 people each year survive such injuries but sustain extensive paralysis

In 2012, Miller published the groundbreaking results of his lab’s efforts to address paralysis. In the years since, researchers at Ohio State and Case Western Reserve University have published proof of concept papers illustrating how similar brain-machine interfaces might work in paralyzed humans.

“It may sound like a sci-fi subplot, but the foundation for all of this work is decades of basic science research,” says Miller, a self-described neuro-engineer who has degrees in physics, biomedical engineering, and physiology. “In our lab, we have been able to eavesdrop on the natural electrical signals from the brain that tell the arm and hand how to move. Our brain-machine interface skips over the spinal cord and sends those same signals directly to muscles.”

This artificial connection from brain to muscles might someday be used to help patients paralyzed due to spinal cord injury perform activities of daily living. Miller’s research was done in monkeys, whose electrical brain and muscle signals were recorded by implanted electrodes when they grasped a ball, lifted it and placed it into a small tube. Those recordings allowed the researchers to develop an algorithm or “decoder” that enabled them to process the brain signals and predict the patterns of muscle activity when the monkeys wanted to move the ball. 

The researchers gave the monkeys a local anesthetic to block nerve activity at the elbow, causing temporary, painless paralysis of the hand. With the help of the special devices in the brain and the arm — together called a neuroprosthesis — the monkeys’ brain signals were used to control tiny electric currents delivered to their muscles less than 40 milliseconds after the brain signals, causing them to contract, and allowing the monkeys to pick up the ball and complete the task nearly as well as they did before. 

Miller will discuss his research at a Science Café event on October 24 from 6:30 to 8 p.m. at the Firehouse Grill, 750 Chicago Ave. in Evanston. Northwestern’s Science Café is free to attend and open to the public.

Topics: