If you’ve been online much this week, chances are you’ve seen the story of Anthony Kulkamp, the 33-year-old banker who played The Beatles’ hit “Yesterday” on guitar while surgeons worked to remove a tumor from his brain. It looks odd–and Darwin knows I wouldn’t want to be conscious while doctors were hands-deep in my skull–but for many musicians, this technique is the best chance they have at continuing to do what they love.

By having a patient exercise important parts of the brain during surgery, say by practicing their craft, surgical teams are able to create a live “map” of important regions, and monitor motor control as they go. “It really is a great challenge for the whole surgery team, including the anesthetist,” says Dr Jean Abreu Machado, who oversaw Kulkamp’s tumor removal. “But it’s worth the trouble if it works.”

Such was the case for renowned violinist Roger Frisch, who underwent a similar procedure in 2014 after he started experiencing tremors in his right hand. “It started [years before],” he recalls. “When I would draw my bow, I suddenly had a shake. Now, for most other professions this wouldn’t be a concern. For a violinist where your career depends on the stability of your appendages, this was of great concern to me. To me the violin isn’t an instrument … it’s part of who I am.”

Doctors agreed “deep brain stimulation” surgery would be the musician’s best shot at restoring control over his hands. The plan was to implant and fire small electrodes in Frisch’s brain to counteract the signals telling his hands to shake. But the problem was, they needed him to play to expose them.

“We actually needed a violin in the OR,” says medical engineer Kevin Bennet. “So we designed a special violin, hooked up to monitors, so he could play during the operation to aid surgeons while they implanted electrodes in the best possible place to stop the tremor.” Today, Frisch continues to be one of music’s foremost violinists, playing for audiences on the world stage.

Perhaps no case of musical brain surgery got more attention then actor and blues guitarist Brad Carter’s 2013 operation to slow his Parkinson’s symptoms. “I’m a finger picker,” he explains. “After medication didn’t work, I was hopeful that the surgery would help me get my hands back. I wanted to record again. I wanted to get on stage again.” Dr Nader Pouratian of UCLA Medical Center performed the procedure, placing a pacemaker in Carter’s brain. “We had to put the device in a very particular place to stop his tremors,” he says. “And keeping the patient awake was the best way to tell if we got it right.”

Carter’s operation was the 500th conscious, deep brain surgery performed by Nader and his team, but it was the first to be done while the patient played music. “Carter asked us if he could bring the guitar into the OR to see if it was working. It was really a unique experience,” he says. “And very effective.”  The surgery was also the first to be live-tweeted, a move the team hoped would keep future patients from being afraid of this kind of surgery. Millions tuned in to watch the 7-hour operation, no doubt calmed by Carter’s bluesy riffs along the way.

If curiosity begs, you can still watch the clips from Carter’s surgery at #UCLAORLive.