Your Brain: The Missing Manual

Mental Fitness

You've now completed your first tour of the brain. Although you don't yet know all the reasons for the peculiar behavior of the planet's dominant species, you now have some of the tools that you can use to start asking the right questions. This makes it a good time to take a step back and change focus from low-level biology to more general guidelines. In this final section, you'll consider how you can keep your mental machine running in tip-top shape through the decades.

First, it's important to realize that the solution isn't to grow a bigger brain. After birth, it's rare for new neurons to appear in the brain. In fact, the story of the brain's development (which is told in Chapter 10) is largely the story of neurons and synapses dying off in waves as your body lumbers into old age. But don't panic yet. There's good reason to think that the loss of a few million neurons over the years is no big deal. In fact, it just might be part of the brain's natural housekeeping.

Rather than count the number of neurons in your head, it's more important to take note of the connections between them. As you've already learned, neurons are constantly being rewired. In healthy brains, the ratio of synapses to neurons grows as the number of neurons declines. In other words, leaner brains can become more efficient to compensate for their loss of neurons.

So what can you do to keep your brain in its best working form? There may be no way to dodge bad genes, bad luck, injury, and disease, ...