Monkeys use only mind control to drive wheelchairs

Neuroscientists have demonstrated a brain-machine interface (BMI) that allows monkeys to use only their thoughts to navigate a robotic wheelchair, according to a study published online March 3, 2016 in the journal Scientific Reports. These results indicate that, in the future, intracranial BMIs could restore whole-body mobility to severely paralyzed humans, the authors predicted.

“In some severely disabled people, even blinking is not possible,” said senior author Miguel Nicolelis, MD, PhD, co-director for the Center for Neuroengineering at Duke University School of Medicine, Durham, NC. “For them, using a wheelchair or device controlled by noninvasive measures like an EEG may not be sufficient. We show clearly that if you have intracranial implants, you get better control of a wheelchair than with noninvasive devices.”

For this investigation, the scientists surgically implanted microelectrodes in the premotor and sensorimotor regions of the brains of two monkeys. As the primates thought about moving toward their goal—grapes in a bowl—the BMI translated their cortical activity into real-time operation of the wheelchair.

Initially, the scientists operated the wheelchair, with the robot’s routes preprogrammed and identical from day to day, while the monkeys sat passively. This “trained” a linear decoder to extract two-dimensional wheelchair movements from the monkeys’ cortical activity.

Next, the monkeys used the wireless BMI to translate their cortical activity into the robotic wheelchair’s translational and rotational motions to navigate the wheelchair toward their goal. As the monkeys learned to control the wheelchair just by thinking, they became more efficient at steering toward the grapes, and they completed the trials faster, Dr. Nicolelis said. (A video accompanying the Scientific Reports article is available here.)

In addition to detecting cortical signals that corresponded to translational and rotational movement, the Duke team also discovered that primates’ brain signals showed signs they were contemplating their distance to the bowl of grapes.

“This was not a signal that was present in the beginning of the training, but something that emerged as an effect of the monkeys becoming proficient in this task,” Dr. Nicolelis said. “This was a surprise. It demonstrates the brain’s enormous flexibility to assimilate a device, in this case a wheelchair, and that device’s spatial relationships to the surrounding world.”

The team now hopes to expand the experiment by recording more neuronal signals to continue to increase the accuracy and fidelity of the primate BMI before seeking trials for an implanted device in humans, he said.

“The current results promise much more than a mere demonstration that monkeys can control whole body navigation,” the authors wrote. These findings suggest that patients with paraplegia who undergo intense BMI training may not only regain the ability to walk using a robotic exoskeleton, but can also recover some sensorimotor and autonomic functions.

“Based on our experimental and clinical observations, we raise the hypothesis that BMIs can lead to partial neurological recovery or even augment brain function because their chronic and continuous use may trigger widespread cortical plasticity and the emergence of new cortical representations. As such, BMIs will likely have a profound clinical impact in the future,” they concluded.