It "Rewires Your Brain?" Think Again.

It seems so archaic: I type with my fingers and I use my hands to drive. Isn't there a better interface than the body? I want devices that can read my mind.

It turns out that's not so far off. In a truly amazing line of research, it has been shown that implanting electrodes in the motor cortex of a non-human primates brain allows animals to control robotic arms without moving their bodies. (Watch a video.) All it takes is some training for the animals to learn to "think" the arm's actions. Just imagine the implications for people who are paralyzed. (Or for people who, like me, are lazy.)

There are also non-invasive brain imaging techniques that allow people, even people who are completely paralyzed, to communicate simple ideas (e.g., answer yes/no questions) entirely with their brains. (Read more.) It requires extensive training. But it's amazing--and may be in our future.

But that's a topic for another post. In the primates' case, this research is an example of literally rewiring the brain. But such examples are rare.

Thus my point: Beware of the phrase "rewires your brain." Put on your sceptic's hat (not the one lined with tin foil) when you see it.

The hype is out there. Consider this amazing internet ad: "Rewire your brain to learn language in ten days!" It's making an impossible claim, but it's also brain-rewiring hype. A recent book called The Shallows warns us that the internet is negatively affecting our thoughts. The idea is that Google is rewiring our brains.

What does it mean to rewire your brain? In one sense, it's trivial: it means that connections between neurons in your brain are changing. Everything we learn is stored in the brain, and the brain can't store information if it doesn't physically change in some (usually routine) way. In this sense, your brain is constantly being rewired, even right now.

This trivial sense of rewiring is like saving a computer file. It changes the state of the hard drive (bits flip on and off, etc). But in a computer, rewiring means opening the sucker up and changing the way the system works. This is the non-trivial sense of rewiring.

In the brain, there is a difference between functional changes (which occur constantly) and structural changes. Structural changes mean, for example, not that you've learned a new piece of information but that the way you learn has changed.

How do you tell the difference? Here's a test: Is the change temporary or permanent? If you think differently because of the internet, would you go back to thinking how you used to if you lost access to the internet for a few days? If so, your brain hasn't been rewired.

Rewiring does happen. For example, London taxi drivers' brains change if they spend years studying to take a test of their ability to navigate the city. Another example is that visual areas in the occipital cortex of the brain are starved of simulation in blind people, so they often take on other functions. This can mean that someone who has been blind since childhood—say, because of cataracts—cannot always learn to see, even if the cataracts are removed.

"Rewires the brain" sounds impressive. It's a tempting phrase. More often than not, though, it's misleading. I'll save my enthusiasm for structural brain changes. Especially if I can type with my mind.

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