The organ that feels no pain

Brain surgery can be done with the patient awake, talking, or even playing the guitar. It seems impossible, but the brain, which processes all the body's pain, feels none of its own.

The reason is that brain tissue has no pain receptors. The skin, the skull, or the membranes wrapping it can hurt, which is why the surgeon anaesthetises them; but once inside, touching the brain itself causes no pain at all.

This makes something astonishing possible: in certain surgeries the person is kept awake so doctors can talk with them while operating, checking in real time that no areas of speech or movement are being harmed.

Source: Johns Hopkins Medicine