Intelligent Neuroprostheses Mimic Natural Motor Control

Users can drive this brain-controlled wheelchair reliably and safely over long periods of time thanks to the incorporation of “shared control” techniques. This wheelchair illustrates the future of intelligent neuroprostheses.

Neuroscientists are taking inspiration from natural motor control to design new prosthetic devices that can better replace limb function. In new work, researchers have tested a range of brain-controlled devices – from wheelchairs to robots to advanced limbs – that work with their users to intelligently perform tasks.

These neuroprosthetic devices decode brain signals to determine the actions their users want to take, and then use advanced robotics to do the work of the spinal cord in orchestrating the movements. The use of shared control – new to neuroprostheses – “empowers users to perform complex tasks,” says José del R. Millán, who presented the new work at the Cognitive Neuroscience Society (CNS) conference in San Francisco today.

Millán, a researcher at the Swiss Federal Institute of Technology in Lausanne, Switzerland, began his career designing autonomous robots that could learn from their own experiences. He then became interested in having these robots help disabled people in a “very natural, direct and intuitive way,” he says. “And what more direct than decoding user’s intention from their brain signals?”

So, Millán began working on “brain-computer interfaces” (BCIs), designing devices that use people’s own brain activity to restore hand grasping and locomotion, or provide mobility via wheelchairs or telepresence robots, using people’s own brain activity.

“The prostheses and robots that our BCIs control are intelligent, as they can interpret many low-level details that are not necessarily coded in the mental commands,” he says. Importantly, they also work autonomously if the users do not want to change their behavior. This function mirrors how our deep brain areas, spinal cord, and musculoskeletal system work together in many routine tasks, allowing our bodies to do simple tasks while we focus our attention elsewhere.

In his and colleagues’ latest work, they tested a variety of brain-controlled devices on people with motor disabilities, in some case quite severe. The participants successfully completed tasks ranging from writing to navigation at similar levels of performance as healthy control groups.

The individuals operated the devices by voluntarily and spontaneously modulating the electrical brain activity, called EEGs, to deliver commands. EEGs have the benefit that they can be recorded non-invasively through probes on the scalp, rather than requiring surgery or sophisticated machinery. “It also provides a global picture of our brain patterns, what is necessary to decode all the variety of neural correlates we want to exploit,” Millán explains.

The participants needed a relatively short training period of no more than 9 sessions before being able to operate the devices. And those using telepresence robots were able to successfully navigate through environments they had never visited. Key to their success, Millán says, was the concept of shared control – using robots’ sensory capabilities to interpret the users’ command in context.

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