It turns out there is a neurological explanation for why people scratch and cut themselves, and spank each other for pleasure. Inflicting small amounts of physical pain, whether from scratching your skin vigorously or doing something more extreme, deactivates the parts of your brain associated with unpleasant or painful emotions. Though scientists have long speculated that there was some kind of neurological payoff from self-inflicted pain, a study published yesterday demonstrated precisely why your brain gets a reward when you hurt your body.
The study focused on scratching, which is a common, slightly-painful thing that everybody does to relieve itches. Researchers stuck people in an MRI brain imaging machine and scratched their legs with brushes for five minutes, watching to see which parts of their brains were active or non-active. Areas associated with painful feelings became less active, as well as areas associated with memory. The researchers say:
We know scratching is pleasurable, but we haven't known why. It's possible that scratching may suppress the emotional components of itch and bring about relief.
It's also possible that the pain of scratching, or more intense pain from cutting, suppresses painful memories too.
The researchers suggest that further study might reveal a way to produce a drug that has the same effects as scratching or cutting does on the brain — thus preventing physical damage while providing the same relief.
Ah, that's the spot [Reuters]
Research suggests why scratching is so relieving [Eurekalert]