What part of the brain has the ego?

Supposedly (at least the neuroscientific researches point this way, so this is very probable) it is located in the cingulate cortex. It is the medial part of the cerebral cortex.

When aware operation and conscious decisions are made, the electrical charge goes trough change in this area.

Some research indicates that schizophrenia is also connected with the change in the structure of this part of the brain.