Over the past year, I’ve spent a lot of time around brains. I’ve held slices of human brains preserved on glass slides. I’ve gazed through transparent mouse brains that look like marbles. I’ve spent a very uncomfortable hour having my own brain scanned (see the picture above). I’ve interviewed a woman about what it was like for her to be able to control a robot arm with an electrode implanted in her brain. I’ve talked to neuroscientists about the ideas they’ve used their own brains to generate to explain how the brain works.

This has all been part of my research for the cover story in the current issue of National Geographic. You can find it on the newsstands, and