Decoding the Brain

STEPS TO UNDERSTANDING BRAIN ACTIVITY AND HOW THE MIND WORKS

- Abha and Deepa Jain

Your brain looks like a pinkish-brown blob of gelatin and may seem just as silent. Don't be fooled by this apparent quietness, though. Around 86 billion nerve cells called neurons form the building blocks of this organ-and they speak. They converse when you're playing, eating, or just sitting still. Some jabber while you sleep, too.

But neurons don't communicate with sound, as you do when you talk. They speak through tiny bursts of electrical energy called action potentials or spikes.

Neurons in the brain send and receive signals using action potentials. It's almost like a language. Neurons in your eyes, ears, and skin produce action potentials in response to lights, sounds, and touch, respectively. And neurons don't just speak to one another. Many relay messages to and from your muscles, telling them whether to contract or relax. Through spikes, neurons in your brain control your whole body, from head to toe.

Coding With One Letter?

All spikes aren't identical. The duration of the signal ranges between one to several hundred milliseconds. (One millisecond equals a thousandth of a second.) Spikes also travel at different speeds. Some spikes plod along. Others whir faster than race cars.

For neurons, though, these differences may not be important. To them, all arriving action potentials may seem like near-identical jolts. It's like they have a language with just one letter, such as an e, instead of a whole alphabet. This is almost like the binary code inside computers, where a signal can only be a I or a 0.

It's easy for programmers to turn words into strings of Is and Os and back again because we invented this code. But decoding the messages of billions of neurons isn't nearly as easy. Could anyone decipher their chitter-chatter?

It's the Number that Counts