Phantoms in the brain

Neurological disorders offer insight into the functions of each part of the brain.

Let’s begin with a thought experiment. Imagine a sort of futuristic helmet with a bunch of wires sticking out of it. When you place it on your head, it fires a powerful magnetic field onto a very small cluster of neurons in your brain – allowing you to activate any part of your brain at will. Actually, this isn’t science fiction. It is a real device called a transcranial magnetic stimulator.

So, let’s say you had access to one of these helmets. Which parts of the brain would you stimulate?

You could, for example, stimulate parts of the motor cortex to make your muscles twitch and flex of their own accord. Or you could stimulate the septum to induce pleasure more intense than the most exquisite orgasm. If you’re blind, you could even stimulate the visual cortex to experience what the sighted describe as “color.”

The point is, whatever part of the brain you chose to stimulate, you’d experience something different. And that’s because the various parts of the brain each have a different purpose.

For example, despite their symmetry, we now know that the left and right hemispheres of the brain are radically specialized for distinct tasks.

The left hemisphere is responsible for, among other things, most aspects of language formation – from the comprehension of meaning to the actual production of sounds. By contrast, the right hemisphere is relatively ineloquent, although it is involved in the more creative aspects of language like nuance and allegory.

Unfortunately, many discoveries about the functions of parts of the brain were only made after something went terribly wrong. For example, the reason we know that the hippocampus plays an essential role in the formation of new memories is that doctors, as a last resort, once decided to surgically remove the tiny, seahorse-shaped structure from an epileptic patient’s brain. After the operation, the patient was no longer capable of forming new memories, although he remembered everything that had happened prior to surgery.

This tragedy resulted in an important discovery – and doctors treat the hippocampus with much more respect because of it. Obviously, experimental surgery that disables patients in the process is far from an ethical research methodology.

That’s why neuroscientists study neurological disorders; they afford an opportunity to examine unique brains without causing any damage.