US scientists have developed a machine that enables people to navigate a robotic wheelchair through their thoughts. "In some severely disabled people, even blinking is not possible," said Miguel Nicolelis, a neuroscientist at Duke University.
"For them, using a wheelchair or device controlled by non-invasive measures like an EEG (a device that monitors brain waves through electrodes on the scalp) may not be sufficient," he said.
"We show clearly that if you have intracranial implants, you get better control of a wheelchair than with non-invasive devices," he added. The researchers used a computer to monitor brain signals from a rhesus macaque.
They recorded signals from hundreds of neurons in two regions of the monkeys' brains that were involved in movement and sensation. During experiments, described in a recent issue of the online journal Scientific Reports, as the animals thought about moving toward their goal, in this case, a bowl containing fresh grapes, computers translated their brain activity into real-time operation of a wheelchair.
As the monkeys learned to control the wheelchair just by thinking, they became more efficient at navigating toward the grapes and completed the trials faster, Nicolelis said.
In addition to observing brain signals that corresponded to translational and rotational movement, the researchers also discovered that primates' brain signals showed signs that 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," 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," he added.
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, Nicolelis said.