During the Cold War, the first implants showing that we could control animal minds sparked panic. The C.I.A. had its own clandestine experimental mind-control program. People warned of brain warfare. Those fears [are] back, along with a conversation about what it means to have freedom of thought at a time when technology is literally being implanted in our brains. Brain computer interface, or B.C.I. ... are very small devices that go right on the surface of your brain, where they can pick up neural activity. The data is transmitted via Bluetooth to a computer program, which decodes the information. In a sense, they're hooked up to an artificial intelligence. So the neural network inside your mind communicates with a neural network outside. And through that, we are able to reconstruct people's intentions. For people with degenerative diseases, or who are paralyzed, or who otherwise have lost important abilities, these implants have been totally revolutionary. These patients can move their hands, type and in some cases, speak again. Optogenetics, a technique for turning isolated neurons on and off, has been used to implant false memories in mice, raising the possibility that, in the distant future, something similar could be done in humans. Neuroprivacy is the idea that we should have to give consent to anyone who wants access to our innermost selves. But there's a question: Does neuroprivacy apply only to my unspoken thoughts? Or does it apply to the electrical activity in my brain?