In a study published last month, UW researchers linked brain activity with paralyzed wrist muscles in monkeys, allowing the monkeys to control movement and overcome wrist paralysis.

The study has implications for use in the control of paralyzed muscles in human patients.

“We hope to create pathways from the brain to muscles that patients can learn to control in order to move paralyzed limbs by thought,” said Chet Moritz, co-author of the study.

He emphasized that human application of the research is years, if not decades, away.

In the study, two monkeys were taught a simple video game before receiving temporary paralysis in their wrist muscles. The game had monkeys use their wrist to push on a joystick, while their brain activity was monitored to see which patterns corresponded to downward or upward movement of their hands.

Researchers then connected a circuit to a neuron in the monkey’s brain to read and analyze the neuron’s activity. When the monkeys played the video game again with paralyzed wrists, their brain activity was converted into functional electrical stimulation (FES), which stimulates muscle using an electrical current.

The type of muscle activity (upward or downward) was determined using brain-wave patterns established before the wrist paralysis. The brain waves were then sorted and, using FES, produced movement.

Researchers were surprised to learn that any neuron, not only motor neurons, could be trained to stimulate muscle movement.

“That was probably the most exciting part of the study,” Moritz said. He noted that this discovery will likely open up doors to even more discoveries.

Scientists need to look into more complex muscle movement and the learning that occurs following the connections between neurons and muscles.

“The number of neurons used will depend on how complex the movement, or the number of degrees of freedom that need to be restored,” Moritz said. “Future works will investigate more than two [connected] neurons controlling larger numbers of muscles.”

An important step before application to humans is reduction of the size of electronics used in the study. Researchers are collaborating with the UW Department of Electrical Engineering to produce more effective and compact circuit designs.

“What’s exciting about this is we can take advancements of wireless technology and device scaling and apply it [to neuroscience],” said Brian Otis, assistant professor and researcher in the Department of Electrical Engineering. “We’re taking all of this equipment and shrinking it onto a single chip.”

After a few years of collaboration with Moritz’s team, Otis and other researchers have created a 1 millimeter by 2 millimeter prototype, which amplifies brain waves from neural activity to be processed and wirelessly transmitted. Their work will be presented at the International Solid State Circuits Conference in San Francisco in February.

The research done on mini-aturization and amplification can also apply to care of the elderly, medical monitoring and even environmental monitoring and military use.

Moritz and his colleagues fused two ideas from previous research: one used FES to stimulate hand grasp using shoulder movement, and another used brain activity to control cursors on a computer screen.

“Our goal was to combine the two techniques to use brain activity to control FES directly,” Moritz said. His study allowed for brain activity to directly control movement.

In the study, researchers employed a technique that used just one neuron to directly control movement, whereas other studies had taken data from hundreds of neurons to produce movement through an algorithm.

“We’re hoping it will create more stable connections, compared to decoding from a large population of neurons,” Mortiz said.

Reach reporter Emily Lee at news@dailyuw.com.