I posted part of this a while back, but the link died:
Sunday, October 12, 2008
Famous Bluegrass banjoist Eddie Adcock strums the banjo, with the rear of his skull removed, while doctors stimulate his brain with electric probes. Why? He suffered from hand tremors which threatened his ability to continue playing. By implanting a pacemaker that can send current to electrodes permanently implanted in his brain, the problem was treated.
For a longer video with the whole background story, watch this, and read this.