How does brain perceive time dilation due to gravity?

This is a common confusion thinking that there is such thing as a "real" amount of time. Time literally runs slower. The brain will think that an hour has passed, and an hour will have passed at that location. Saying "in reality 7 years passed" is incorrect. "7 years passed on Earth" would be correct.

All physical processes will slow down in that gravity well; all clocks will run slow. Since the brain contains physical processes (chemical reactions, electrical impulses, etc.) these will run slow too and for this reason, a person in that gravity well who looks at their wristwatch will not be able to detect the fact that it is running slow, because their brain is too.