To drive to my parents’ place from my place, Google Maps tells me to be sure to catch the ferry.
From Australia to Japan, sorry, driving directions dictate you’ll have to kayak.
With your car.
Maps are great. And one of the cool things about Google Maps is that there is often another way to solve your problem.
For thousands of amputees, seeing a map differently would make a world of difference.
The itch you couldn’t scratch
Amputees often complain of an itch, or even unbearable pain, in the limb they’ve lost. Naturally, the limb isn’t there, which is how we got the terms phantom limb and phantom pain. The itch, or the pain, exists only in the brain.
There’s no doubt that it feels completely and utterly real and that the pain is, in some cases, disabling.
But still, for all that, only in the brain.
And you can’t scratch your brain.
So how do you scratch an itch on a limb that isn’t there?
By realizing you’ve got the wrong map.
Stay with me…
Phantom pain can exist for a number of reasons, but one of the coolest treatments comes from map reading, some neural sleight of hand and an impressively large mustache.
Enter Vilayanur Ramachandran.
In his spare time he busies himself with the archaeology of the Indus Valley, so map reading and topography may be hitherto untapped talents.
By day, however, he is transformed into a modern-day, mustachioed, brain superhero.
Click the link – you’ll see he really is a superhero, and done plenty, and it’s his work with phantom itching that’s of interest to us here.
And it’s particularly how the brain handles things like this that is so tricky.
You already know that different brain functions are located in different places in the brain. We’re concerned here with the sense of touch, which is located in the primary somatosensory cortex, in the parietal lobe.
The somatosensory cortex
This is a strip of your cortex (what you see on the outside of the brain) that runs from the top of your ear, over the top of your head, and down to the top of your other ear. The picture underneath is a slice through the brain at this point.
Here, you’re looking at the left half of someone’s brain, front on.
Over the top of the brain, on the parietal cortex, you can see a map of the body, in which the picture shows where on the cortex various body parts are represented. The map is mirrored on the other side of the brain.
You’ll note that the picture is not to scale, and some parts are disproportionately larger or smaller on the brain than in reality. Where the body parts are bigger, it’s showing that there is more brain space devoted to that body region.
In those areas, you’d also find more sensitivity and activity. Compare the sensitivity of your face (high) with that of your leg (low) and you can see why more brain space is devoted to your face.
So when you get something amputated, and that bit no longer exists and can no longer be touched, what happens to the piece of brain space that was used for that bit?
Well, in Human Resources speak, it gets redeployed. Your previous position is redundant, ma’am, and you’ve been redeployed. In map speak, the map gets re-drawn and the neural cartographer redesigns how it looks.
In real life, it means that the neighboring body parts on the map take over that part of the brain.
So have a look at the map, and find the hand. Now imagine deleting the hand from the picture, and stretching the remaining picture to cover over the gap.
The point on the brain that used to be dedicated to the hand, is now dedicated to what was next to the hand. The face.
And if you had pain in the amputated hand, or an itch that you couldn’t scratch, what would you do?
Because the itch is in your brain, and not on your amputated hand, we need to scratch the bit of brain that’s where your hand used to be.
Which means that the itch on your phantom hand is, for the brain, in an area that now controls the face. So go on, scratch your cheek. You might need to move around your cheek a little but, that’s where it will be.
Which is what Ramachandran, mustachioed map hero, figured out. And which was great news for a large number of itchy people. Told you he was a superhero.
Seeing the brain take over like this, and reorganize itself by re-mapping where things went, was proof that the brain was not fixed in what it did. It was flexible, perhaps even more than we suspected, and certainly more than just with somatosensory maps.
It was capable of gradual, even swift, reorganization, redeploying functions to different locations. In the parlance of brain things, it was plastic, meaning malleable, or capable of being shaped. Think plastic as in plasticine.
That it had the ability to move functions around was further clear evidence of the brain’s ability to change itself. There had already been evidence that it was possible but, with the prevailing view being that brain function was
- localized and
it was going to take something impressive to overturn the majority. And when the majority think in terms of fixed function, it is something of a heresy to suggest that we can scratch an itch on a phantom limb by scratching the face.
Sounds obvious now…
So here’s the take home bit
Now that we know that the brain can reorganize, grow new cells, adapt and re-map at short notice, what could we do with that knowledge? Plasticity presents extraordinary opportunities.
How could we build better brains, stronger minds, more resilient people?
Could we prevent, or at least delay, brain-based diseases?
What would it change about education, or parenting, and health?
What do we do that compromises what is a natural brain ability, and how do we fail to take advantage of it?
Impressive words to drop into the morning coffee chat
Vilayanur Ramachandran, Primary Somatosensory cortex
What do you think?
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