 So in the mid-60s, these pacemaker researchers noticed something weird. They were looking at chronic back pain, and they found that if you dropped a pacemaker wire into someone's spine at just the right place and sent out little pulses of electricity, the pain went away. For people with back pain, it was great news. Instead of taking all these pills, they could just get one implant that would take care of it. So then they thought, this works great on the spine. What happens if you do it to someone's brain? It turns out it does a lot. I call it deep brain stimulation or cortical stimulation. If you put the wire in just the right place, you can stabilize a person's Parkinson's, tremor, stop seizures, treat depression. It all depends where you put the wire. The problem is we still don't know very much about how the brain works. We know brain cells are passing along electrical signals in something that looks kind of like a circuit, but most of the stuff is still trial and error. Our best theory is that if you have a seizure, that's a circuit going bad, looping out of control, and the right electrical pulse at the right time can reset it. So if we can disrupt the circuit that gives someone depression, maybe putting the wire in a different spot will disrupt the circuit that makes us forget things or get distracted. And a lot of people are looking for that spot. You see a lot of patents for enhancing memory this way, even if none of them really work. The closest thing we've got is transcranial stimulation. It's basically an electric hat that sends pulses through your scalp. As it turns out, it really does help you pay attention and remember things better. You get a little bit worse at automatic tasks, but it doesn't matter. The interesting thing will be when we can actually use this technology to make more effective brains, not just cure diseases or run experiments. We're already doing this with chemicals. If I want to be more alert, I drink some coffee. If I want to relax, I drink a beer. Those are just chemicals that go into my blood and then go into my brain. What if we could do that with electricity? What if I could just turn it on and off by flicking a switch? What if I could give myself a perfect attention span for two hours while I'm studying for this final and then turn it off completely? Of course, we're going to have to know a lot more before we get there, but someday the same command doctors have over the body, they could extend to the mind itself.