It began in early October 2017, when 108 stroke patients with significant arm and hand disabilities turned up for a peculiar clinical trial. The researchers would be surgically implanting a neurostimulator to their vagus nerve, the cranial nerve that runs along the groove in the front of the neck and is responsible for transmitting signals from the brain to other parts of the body. By the time the trial concluded, the subjects’ once limited limbs had begun to come back to life. Somehow, pulses to that nerve combined with rehab therapy had given the patients improved use of their disabled limb—and …
