Spirit/will has been demonstrated to possess the necessary capability to overrule the brain. It's a choice. Maybe not an easy one to make, but a choice nontheless.
There are some things controlled by your nervous system that you can't override though, like your digestive system and your heartbeat. Influence yes, but to an extremely limited degree. It seems very likely to me that there are some processes in the mind as well that cannot be consciously overridden.
That is a curious response on these boards (I'm glad to see it). My name is h0p3. It's a pleasure to meet you. I am not here to argue with you, but I would like to hear more of your thoughts and feelings on the matter.
Not sure what a "spirit" is, but in order to make a choice you actually use that same brain - so it's not overruling itself.