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It looks like a simple video game, but the innovative new system might one day restore physical control to the lives of people with paralysis.
Neurosurgeons from Stanford and Brown University implanted microelectrodes in the brain of a paralyzed research participant, connecting him to a computer to enable electrical signal transmission. The test subject, through the microelectrodes, was able to pilot a virtual drone through a video game-like obstacle course using only his thoughts. The achievement, as detailed in a January 20 study published in the journal Nature Medicine, holds important implications for enabling people with paralysis to enjoy activities previously inaccessible to them, and perhaps one day regain autonomous movement.
“We developed a high-performance, finger-based brain–computer-interface system allowing continuous control of three [virtual] independent finger groups of which the thumb can be controlled in two dimensions, yielding a total of four degrees of freedom,” the researchers wrote in the study. Though scientists have used brain-computer technology for over a decade to assist people with paralysis, it has historically faced challenges in replicating complex movements, such as those of the fingers, according to a Nature statement.
The participant in the study is a 69-year-old right-handed man who suffered a spinal cord injury that gave him tetraplegia, an extreme form of paralysis that impacts most of the body. As detailed in the new paper, microelectrodes were implanted into his left precentral gyrus, the part of the brain that controls hand movement. The neurosurgeons asked the participant to watch the movements of a virtual hand, and then used artificial intelligence to identify the electrical brain activity associated with particular finger movements.
This association then allowed the AI system to predict the desired finger movements, even though the participant can’t move his own fingers. The brain–computer interface thus enabled him to control the movements of a virtual hand using his thoughts. The virtual hand was divided into three segments, which he could move vertically and horizontally, sometimes simultaneously: the thumb, index and middle finger, and ring and pinkie.
“This is a greater degree of functionality than anything previously based on finger movements,” Matthew Willsey of Stanford University, who led the study and is also an assistant professor at the University of Michigan (U-M), Ann Arbor, said in a U-M statement. With practice, the participant was able to use this brain–computer interface to control the movement and speed of a virtual drone in a simulated obstacle course, akin to how people without paralysis use game controllers to play video games.
The interface “takes the signals created in the motor cortex [in the brain] that occur simply when the participant tries to move their fingers and uses an artificial neural network to interpret what the intentions are to control virtual fingers in the simulation,” Willsey added. “Then we send a signal to control a virtual quadcopter [drone].”
“The quadcopter simulation was not an arbitrary choice,” as the “research participant had a passion for flying,” said Donald T. Avansino of Stanford University, who also participated in the study. “While also fulfilling the participant’s desire for flight, the platform also showcased the control of multiple fingers.”
The microelectrodes’ in the participant’s brain are physically wired to a computer. Less invasive approaches, including electroencephalography (EEG, a painless technique that measures electrical brain activity without the need for surgery), have previously enabled patients with paralysis to play video games. However, the researchers suggest that fine motor control is better achieved by working more closely to neurons, according to the U-M statement. In fact, they noted in the study that their brain–computer interface enabled the participant to control the drone six times more accurately than a similar previous study that used EEG.
While the ability to play a video game enables patients with paralysis to socialize and engage in leisure activities, precise dexterous control has even greater potential.
“Being able to move multiple virtual fingers with brain control, you can have multi-factor control schemes for all kinds of things,” explained Jaimie M. Henderson of Stanford University, who also participated in the study. “That could mean anything, from operating CAD software to composing music.” In other words, such technology could enable patients to pursue broader activities and even careers that were previously impossible for them.
While Star Wars‘ characters use “the force” to control objects at a distance, scientists are leveraging technological advancements to help patients with paralysis regain control over their lives.
