Welcome to the future, ladies and gentlemen: Scientists have taught monkeys to navigate a room using a mind-controlled wheelchair. Their study, published today in Scientific Reports, could help anyone paralyzed in their arms and legs gain greater control and independence.
"The wheelchair remains the main device to assist navigation in people with motor disabilities, particularly those suffering from severe cases of body paralysis," write Duke University postdoctoral fellows Sankaranarayani Rajangam, Po-He Tseng, and their team. Yet for someone with severe disabilities, controlling a wheelchair is no easy task. Until recently, navigation has meant mastering tricky joysticks or relatively crude "brain-machine interfaces" (BMIs), such as electroencephalogram-based devices that use electrical brain signals recorded on a person's scalp to control an electric wheelchair. Similar technologies have been used as the basis of mind-controlled artificial arms and legs, but scientists' real dream has been to build a direct link between the brain and a wheelchair. In theory, a BMI directly linked to neurons in the brain (rather than electrical signals recorded on the scalp) would allow a person to develop more precise movement control than is possible with EEGs.
All the pieces you'd need for a mind-controlled wheelchair have already been built and tested.
As much as that might sound like a science-fiction pipe dream, all the pieces you'd need for a mind-controlled wheelchair have already been built and tested. Back in 2002, for example, researchers got rhesus macaque monkeys to control a cursor on a computer screen using tiny electrodes implanted in their brains. Other have trained monkeys to control real-world robotic arms and simple joysticks using similar brain implants.
The new study is a natural extension of that work, the researchers say, but with a twist: Rather than needing to think about controlling an arm or a joystick, Rajangam, Tseng, and their team trained macaques using a "whole-body" approach. First, two monkeys sat in robotic wheelchairs that drove them to and from a grape dispenser. At the same time, a computer recorded electrical signals from about 140 neurons in the sensorimotor cortex, a brain region responsible for planning and controlling movement. In theory, those recordings helped a computer learn to translate brain signals into corresponding wheelchair motions.
Next, the team turned over control to the monkeys—instead of controlling the wheelchair and recording brain activity, the researchers now used the monkeys' brain activity to control the wheelchairs. Even on the first day of testing, the two macaques could move their wheelchairs around a room toward the grapes, and over the course of several weeks they managed to reach their targets more quickly and with fewer accidental detours.
In the near term, EEG-based devices are likely to be more popular, in part because they don't involve brain surgery and the risks associated with it. "However, as intracranial recording systems improve in efficiency and safety, they will likely become more attractive to the clinicians and patients, particularly those suffering from devastating levels of body paralysis," the team writes.
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