Our new study “Direct Cortical Control of Primate Whole-Body Navigation in a Mobile Robotic Wheelchair” presents the first demonstration of wheelchair navigation enabled through a cortical brain-machine interface (BMI).
Previous neurophysiological and BMI research in primates mostly focused on eye and arm movements, whereas brain mechanisms of whole-body movements (for example, jumping from one tree to another) were virtually neglected. This is a serious impediment to the development of invasive BMIs for wheelchair control. Such devices are needed for patients suffering from severe body paralysis.
Rajangam et al. for the first showed that rhesus monkeys can navigate themselves while seated in a wheelchair, using their cortical activity as the control signal. Monkeys were chronically implanted with multichannel electrode arrays, which recorded from several hundred cortical neurons in the sensorimotor cortex. The BMI transformed this neuronal ensemble activity into wheelchair linear (backward and forward) and rotational (leftward and rightward) velocity.
Monkeys successfully learned to navigate the wheelchair from one corner of the room to the other corner, where a food reward was placed in a feeder. Their ability to drive the wheelchair improved over several weeks of training. The navigation did not require any steering device (for example, a joystick); monkeys produced the wheelchair movements just by imagining themselves moving.
The demonstration was possible owing to Tim Hanson’s multichannel wireless recording system and brilliant engineering of Gary Lehew, Po-He Tseng and Allen Yin.
There is still a long way till invasive BMIs of this type could be implemented in human patients. But a proof of concept demonstration is there!