What do epilepsy, an out of body experience and your personal space bubble share in common? Mother-and-son science writers Sandra and Matthew Blakeslee explain the connection in their book, The Body has a Mind of its Own.
Team Blakeslee begin their story in an unlikely place: the region of your brain behind your right ear. It’s known as your Right Angular Gyrus (RAG).
Before an epilepsy operation, the surgeon’s standard procedure is to open up the skull and poke around a little to identify the various functional brain areas.
Even though human brains share the same essential architecture, each brain is wired slightly differently. A quick round of poking and prodding is the best way to get a sense of the layout, and thus to know what not to cut.
Since the brain doesn’t feel pain, this recon mission is done with the patient awake. The surgeon probes a given area, and the patient reports back what they are feeling. For example, a gentle touch on one area of your brain might register as if someone is tickling the big toe on your left foot. You get the idea.
One day, a neurosurgeon enacting this procedure happened to probe the patient’s right angular gyrus. Much to the surgeon’s surprise, the patient excitedly explained that they had the sensation of hovering above the operating table and looking down on their own body. The same thing has since happened to others as well. It turns out that at least some of the time, the classic out-of-body experience is as simple as knowing where to poke.
So what’s going on? In trying to predict and understand its environment, the brain constructs maps of the real world. This is how we can remember the floor plan in our house or apartment, or find our way back to the grocery store again and again.
In a very literal way, your sense of self reaches beyond your own skin.
In fact, your brain annexes and maps the area around you as if it were an extension of your body, albeit a virtual one. Scientists call this zone “peripersonal space.” The out-of-body experience, from the brain’s point of view is not so ‘out of body’, it’s just working from a different definition of where your body begins and ends.
This makes the use of tools in our lives much more meaningful. When a baseball player picks up a bat, his brain treats the bat as a logical extension of his own arm and hand. In the same way, an experienced backhoe operator’s command of the machine’s joystick turns the machines bucket into his own giant robot arm, thus extending his reach in an entirely literal way.
The Blakeslees also point out that your peripersonal space is not static, but “morphs” based on your movement and intentions. This is why a sight-impaired person can learn to navigate so well with a cane.
And as they make the way down the street, even though they are holding onto nothing but a glorified stick, their extended brain mapping allows them to feel the texture of the pavement, and extract a very real sense of the ground they are traversing.
So the next time you’re riding on a subway or find yourself crammed into a crowded elevator, keep in mind that you’re encroaching on some stranger’s peripersonal space, and from the brain’s perspective, you’ve just shared a very intimate moment.