Neuroscientist Greg Gage demonstrates in a recent TED Talk how one person’s brain can be used to control another person’s arm. With the help of two volunteers on stage, Gage uses an inexpensive setup to read the nerve impulses from his first volunteer, Sam, and relay those impulses through a “human-to-human interface” into the arm of his second volunteer, Miguel. Once the setup is properly configured, whenever Sam moves her hand it causes Miguel’s hand to move involuntarily.

A video on Gage’s site Backyard Brains demonstrates the human-to-human interface in more detail, including what items are needed to construct the device, and how to properly connect it to the test subjects.