For every action, there’s a reaction. And for many movements we make, there’s an intention: we think about moving, and we move. Now a study published in the May 8th issue of the journal Science suggests that the experience of moving is all in your mind. Because the part of the brain that’s active when you intend to move is the same part that lets you feel like you did.

Two separate brain regions are involved in moving your body. One part provides the intention, and the other powers the actual movement. But researchers didn’t know which part let you know that you actually moved.

In the new study, scientists were working with patients undergoing surgery to remove a brain tumor. Surgeons often electrically stimulate the area around the tumor while the patient is awake and can provide feeback, so they can avoid damaging critical tissue. The scientists found that zapping one particular part of the brain made their patients feel like they wanted to move their arms, lips or tongue. And ramping up the stimulation to that spot made them feel like they’d done it. But when the team poked at the region that actually caused motion, the patients didn’t know they moved—a finding that’s oddly moving.

—Karen Hopkin