Fundamentally, the brain is a prediction machine, and that is the driving engine behind its constant self-reconfiguration. By modeling the state of the world, the brain reshapes itself to have good expectations, and therefore to be maximally sensitive to the unexpected.

For a short time, the government of France forced newly released prisoners to marry local prostitutes, and then the newlywed couples were linked with chains and shipped off to Louisiana to settle the land. But even these French efforts were insufficient.

What if you could detect not only the magnetic field around objects but also the one around the planet? After all, animals do it. Turtles return to the same beaches on which they were hatched to lay their own eggs. Migrating birds wing each year from Greenland to Antarctica and then back again to the same spot. Pigeons who carry messages between

Consider one-trial learning, in which you touch a hot stove once and learn not to do it again. Emergency mechanisms exist to make sure that life- or limb-threatening events are permanently retained. But

The system puts enormous work into shifting itself to a point where it can maximize information.

If a blind person passed her finger repeatedly over the bumps of Braille, but had no motivation to learn it, no rewiring would occur, because the right neuromodulators would not be present. Similarly, if adding a new telelimb to your body has relevance to you, your body will learn it—just as Faith the dog mastered a unique body plan.

Marrying the flexibility of the brain to the burgeoning creativity of the VR design world, we’re moving into an era in which our virtual identities will no longer be limited to the bodies that we happen to have evolved.

Recall Fred Williams, who (unlike Serena and Venus) hates tennis. Why doesn’t his brain change, even after the same number of hours of practice? Because these neuromodulatory systems are not engaged. As he drills backhands over and over, he’s like the rats grabbing the pellets without the acetylcholine.

Contrary to first glance, memory is not one thing, but instead comprises many different subtypes. On the broadest level, there is short-term memory (remembering a phone number just long enough to dial it) and long-term memory (what you did on that vacation two years ago). Within long-term memory, we can distinguish declarative memories (such as