I thought vision was something that I could describe as a one-directional process– photons hit your eyeballs, the eyeballs send that information to your brain, your brain starts by detecting some edges, and it turns those edges into shapes and into objects and scenes, and it’s just this feedforward one-directional process. And there are a few milliseconds during which the input is the best way to describe what’s happening in your brain. It’s just taking pictures of your brain, but it subtly changes in intensity as the blood flow changes and I can see which part of the brain is working harder on which part of my task. And so I want to know how your brain can tell that this image is a transition from one thing to another. In your brain, there’s like 100 billion neurons.