When the 'Self' is not the body then question of brain does not arise because self pervades in everything and everywhere in all the three states.

Sri, Sankara declares: - the world is myth and Brahman alone is real then why to worship the guru and gods based on the ego, which is false self of this   false world.

When Sri, Sankara says: world is unreal. He never said body is unreal. He would have said only birth and death is unreal but he did not say that, he said the world is unreal.   He meant   the world including the body, because the body and world appear together and disappear together [waking/dream].  Then we have to think, what remain without the body and the world as reality. 

How can the birth, life, death, rebirth, and reincarnation, which take place in unreal world [waking or dream], can be true.   The experience of birth, life death, rebirth, reincarnation takes place   within the unreal universe, which appears as waking or dream (duality)   and disappears as deep sleep (non-duality).  The one which appeared as waking or dream diapered as deep sleep is formless consciousness (soul), the innermost self. 

Soul or consciousness is the innermost self is birthless and deathless but it is the witness of the coming and going of the three states. 

When the whole world is unreal than one has to realize the fact that, the body and ego are reality within the unreal world therefore, the  body  and the world  are part of the falsehood, than what is the use of thinking on the body base when the self is not physical. 

If dream entity imagines in the dream that: - The self’s manifestation is in the brain. The passage from the Heart to the brain might be considered to be through the sushumna, or nerve (nadi) with some other name. The sushumna or such nadis are all comprised in Para, i.e. the Atma nadi. --

 – the dream becomes unreal when waking takes place. 

Therefore if the waking entity thinks the same way in the waking experience that:- The self’s manifestation is in the brain. The passage from the Heart to the brain might be considered to be through the sushumna, or nerve (nadi) with some other name. The the sushumna or such nadis are all comprised in Para, i.e. the Atma nadi. --- 

–--- the waking also becomes unreal when the waking entity realizes, it itself is not the self. If the self is neither the waking entity, nor the self is dream entity, but the self is the formless soul, which is the witness of the coming and going of the three states.  On the standpoint of the soul, the innermost self, the three states are non-existent as reality.   When the 'Self' is not the body then question of brain does not arise because self pervades in everything and everywhere in all the three states.

The scientists now concluded that you are not the brain [body]:-

Consciousness requires the joint operation of brain, body and world. "You are not your brain. The brain, rather, is part of what you are."

The Biology of Consciousness
by Alva Noë. Hill and Wang, 2009

                                                                            

Alva Noe, a University of California, Berkeley, philosopher and cognitive scientist, argues that after decades of concerted effort on the part of neuroscientists, psychologists and philosophers "only one proposition about how the brain makes us conscious ... has emerged unchallenged: we don't have a clue." The reason we have been unable to explain the neural basis of consciousness, he says, is that it does not take place in the brain. Consciousness is not something that happens inside us but something we achieve it is more like dancing than it is like the digestive process. To understand consciousness the fact that we think and feel and that a world shows up for us we need to look at a larger system of which the brain is only one element. Consciousness requires the joint operation of brain, body and world. "You are not your brain. The brain, rather, is part of what you are."

Thus, it is going in the right direction in its invention and one day it will declare that everything is consciousness, which  Sri, Sankara declared 1200 years back –everything is Atman- because Atman is in the form of consciousness.  Thus we have to know the fact that Buddha, Goudpada and Sri, Sankara are not only reformers but also the greatest sage scientists. Since there original thesis have been lost in the labyrinths of philosophy and mutilated by orthodoxy, it becomes very difficult understand and assimilate the wisdom expounded by the great masters. In addition, the conservativeness of the scholars will not allow any research other than playing with the words, which suits the mass mind sets, because of their egocentric outlook. 

Seeker has to do his own home work in order to understand and assimilate the real fragrance of the wisdom expounded by the great masters. It is a hurricane task.  Thus, it is no use going through all the scriptures, when there is direct path to non-dual truth.  The same time and effort can be used to reach the non-dual destination, which lesser time and effort.     

Self-Knowledge or Brahma Gnana or Atma Gnana  is meant only for those who have intense urge, and courage to accept the truth with humility and reject the untruth. Since people start comparing with their scriptural knowledge, it becomes impossible to assimilate and realize the non-dual truth.   Therefore, there is no need to convince anyone other then our own-self to get the firm conviction.  I am not trying to prove my views, but it is for you to prove yourself to know what is truth? and what is untruth to assimilate the Self -Knowledge or Brahma Gnana or Atma Gnana.