This news story was first published in print and online by The Medical Republic on the 7th October 2015.
Neural prostheses are now able to restore some independence to people paralyzed as a result of stroke, spinal cord injury or neurodegenerative disease.
Researchers from Stanford University implanted 4×4 millimetre microelectrode arrays into the motor cortex of two patients with advanced amyotrophic lateral sclerosis.
The patients were wired up to a computer screen and showed exceptional precision and speed at moving a cursor around to select targets. One of them was also able to use a visual keyboard interface to ‘type’ six words a minute.
The 96 microelectrodes pick up a field of neural activity in response to the patient mentally moving their index finger as if on a touch-pad. But it’s not a case of plug and play. The patient has to imagine these actions many times over to allow the software learn how to distinguish the signals from background neural activity and then decode them.
“Following decoder calibration participants are able to immediately control the cursor,” says Dr Jaimie Henderson who led the multidisciplinary research team. In an earlier pilot study, performance had been slow and jittery. But with improved decoding algorithms the on screen response was reduced to just twenty milliseconds allowing patients to correct errors much more quickly.
Another problem of translating the technology from the lab to the real world is all the electromagnetic noise in the environment. Dr Henderson explains: “We also introduced noise reduction and filtering innovations that allowed us to improve the quality of the recorded neural signals in the participant’s homes.”
While the technology still requires some trouble-shooting in the lab, it may not be too long before paralysis patients will be able to navigate a computer operating system, command an motorised wheelchair or even operate a robotic limb using mental commands.
More information on the trials is available at www.braingate.org.
Nature Med; online 28 September 2015