Are neurons located only in our brains? And also, when we are in a coma, what happens to our neurons?

the brain is the only place you wil find brain nurons and when a person is in a coma the brain is not running at a fast alert as it would if u where awake the brain is working at a really slow alert speed becuase u wont be able to jus shake and wake a person out of a coma becuase the brains nurons are working slow