Livewired: The Inside Story of the Ever-Changing Brain

Some years ago, the writer Stewart Brand proposed that to understand a civilization, you need to look at multiple layers functioning simultaneously at different speeds.22 Fashion changes rapidly, while the business pursuits in an area alter more slowly. Infrastructure—such as roads and buildings—evolves more gradually. The rules and laws of a socie

Consider the precipitous drop in American crime in the mid-1990s. One hypothesis is that the drop stemmed from a single piece of legislation, the Clean Air Act, which required automobiles to switch from leaded gasoline to unleaded. With less lead in the air, crime saw a significant drop twenty-three years later. It turns out high lead levels in the

play a loud beep to someone, and use electrodes on the scalp (electroencephalography) to measure the brain’s response. In a normal adult, the beep elicits an electrical response that can be measured clearly over the auditory cortex, but is smaller or absent over the visual cortex. Now compare this with what you would see in a six-month-old child: t

When you walk around your home, you pay little heed to the environment, because you already have a good model of it. In contrast, when you’re driving in a foreign city, trying to find your way to a particular restaurant, you are forced to look around at everything—the street signs, the store names, the building numbers—because you don’t already hav

One strategy is to turn on plasticity when events in the world are correlated. That is, encode only those things that co-occur, such as seeing a cow and hearing a moo. In this way, related events become bound together in the tissue.

brains are most flexible at the beginning, in a window of time known as the sensitive period.5 As this period passes, the neural geography becomes more difficult to change.

We suggest that dreaming exists to keep the visual cortex from being taken over by neighboring areas. After all, the rotation of the planet does not affect anything about your ability to touch, hear, taste, or smell; only vision suffers in the dark. As a result, the visual cortex finds itself in danger every night of a takeover by the other senses.

Reflect the world. Brains match themselves to their input. Wrap around the inputs. Brains leverage whatever information streams in. Drive any machinery. Brains learn to control whatever body plan they discover themselves inside of. Retain what matters. Brains distribute their resources based on relevance. Lock down stable information. Some parts of

It tries to constantly change its circuitry to maximize the data it can draw from the world. To that end, it builds an internal model of the outside, which equates to its predictions. If the world proceeds as expected, the brain saves energy.

The highest level—where the best learning occurs—is achieved when a student is invested, curious, interested. Through our modern lens, we would say that a particular formula of neurotransmitters is required for neural changes to take place, and that formula correlates with investment, curiosity, and interest.