Brain implants that treat disease

The NeuroRestore group has also been working on treatments for Parkinson’s disease. People with Parkinson’s can be prone to falls and what’s known as freezing gait: a sudden stopping of

movement or inability to move, especially when approaching a doorway. In a study published in November 2023 in the journal _Nature Medicine_, Moraud and colleagues unveiled a system that

uses a spinal implant in concert with four inertial sensors — like the ones that detect when a smartphone is tilted at an angle — to correct the walking gait of a person with Parkinson’s.

Unlike DBS, which adds electrical “white noise” to the brain, this system predicts which kinds of signals ought to be reaching the spine and sends those out into the spinal cord. This system

uses a sophisticated model of how nerve signals activate the body’s muscles to automatically correlate the person’s gait with the nerve signals that the brain should be sending to the legs.

It then sends corrective pulses of electricity to electrodes surgically implanted next to the spinal cord. When using the implant in combination with three months of physical therapy, the

study’s main test subject — a man from Bordeaux, France, named Marc Gauthier, who was 62 at the time of the study — saw his freezing gait almost vanish and the overall quality of his walking

gait improve. Gauthier has been using the device for roughly three years, for about eight hours per day. He now takes miles-long nature walks around a lake. “I can walk better, I am less

unbalanced, and I think that stairs don’t scare me anymore,” he said in patient testimony included with the 2023 study. “Now, I can walk five kilometers without any stops.” _RESTORING

SPEECH_ Other research teams are working to restore speech in people who have lost it. Two studies published side-by-side in _Nature_ in August 2023 unveiled brain implants that could

synthesize speech from recordings of brain activity. Working at between 60 and 70 words per minute, these systems are currently about half as fast as natural conversation — but they are

more than three times as fast as similar systems that came before them. One of these systems, developed by a team led by University of California, San Francisco neurosurgeon Edward Chang,

M.D., even came up with a way to use brain activity to animate a digital avatar. This study’s participant, a 48-year-old woman named Ann Johnson, suffered a stroke in her brain stem in 2005

and was left paralyzed and unable to speak. The system could decode Johnson’s brain activity and decipher her intentions to move her facial muscles and vocal tract — and then translate these

signals into synthetic speech and corresponding animations of a digital face.