Made four years ago now, this clip shows musicians wearing headsets that can pick up their brainwaves. By learning to control their own brainwaves the musicians play their instruments directly and coordinate their playing to make music.
Brain electrical potentials are directly affecting the outside world. Headsets like these can be used for computer gaming and many other purposes.
This type of work is leading to rapid advances in medical science. For example amputees can learn to control prosthetic limbs, though to achieve the best results electrodes have to be implanted into the brain.