Living bluegrass legend Eddie Adcock needed brain surgery to stop hand tremors that threatened his livelihood. So, doctors put in a pacemaker-like device, which sends electric current to parts of Adcock's brain in order to quell his shakes. To find the spots that controlled his hands, the medical staff had him play the banjo while they inserted their electrodes. BBC has video of the surgery, which took place at Vanderbilt Medical Center in Nashville, Tenn. Watch as Adcock's plucks and strums guide the surgeons' hands.