[Joeri]

Internal to what? The brain is not a monolithic thing, it is different parts communicating and interconnecting. When the connection between the halves is cut, the person objectively becomes two people, but still experiences and presents themselves as one. Observing ourselves is just one part of the brain responding to another, or theorizing on past behavior. There is probably no actual introspection going on inside of the human brain, only the perception of one.

[IsTom]

Internal as in that which is feeling things. In this context the physical brain is what is responsible for what you do and feel, but it is not physically different from other matter and it requires no "internal observer" do do its thing.