Video of December 13 broadcast on WCVB-TV

Every year, 800,000 people will have a stroke, potentially leading to limited mobility and even paralysis. Those conditions happen when brain neurons die, deprived of the blood they need. Now, a new study is focused on the neurons still functioning in the brain.

Rick Doyle suffered a stroke in 2017 while trying to climb up the stairs at home.

"I didn't make the step and something was wrong, so I kind of spun around and lost my balance a little bit," Doyle said.

He spent three weeks in the hospital. His left arm and leg were unresponsive. Once he was released and returned home, a new normal set in.

"I love to fish, and that's one of the things (I couldn't do). I couldn't crank the reel anymore," said Doyle.

"One of the most disabling effects of the stroke is the loss of the ability to use the arm and the hand," said Dr. Leigh Hochberg, the director of the Center for Neurotechnology and Neurorecovery at Massachusetts General Hospital.

Hochberg and his colleague, Dr. Teresa Kimberley, director of the Brain Recovery Lab at MGH Institute of Health Professions, are co-authors of a study helping people like Doyle recover some of what was lost.

"(We're) trying to re-teach the brain to find a new way to do what it can't do because of the stroke," Kimberley said.

They're testing a technique called VNS, or vagus nerve stimulation. It's been used in the treatment of epilepsy for years.

In this study, a neurostimulator is implanted in the chest wall and a cuff electrode is wrapped around the vagus nerve in the neck. The nerve is unique in that it directly connects to the brain.

In therapy, each exercise repetition is paired with a mild electrical pulse, that stimulates the vagus nerve.

"You want to engage the neurons that are left, that are still viable. You pair this pulse with each repetition of that practice that you're doing and you get more activity in those neurons," Kimberley said.

In the study, participants who received VNS showed significant improvement after 90 days compared to those who did not receive it. For Rick Doyle, that meant getting back to the things he loves, including fishing.

"I now am able to crank it back in without any help. It's definitely improving, so I think next year, I'll be able to use that without any aids to fish," Doyle said.

The device is still a few years away from being available to everyone, but the study is still enrolling participants.