So the question still remains, what is the seeker? I think the most important tangible component would be attention which I believe is outside the brain. It is like the torch that illuminates reality and changes the brain accordingly. I guess the ultimate tool we have is attention. If we can train one pointed attention, we can use it on any conceivable thing.
I read an interesting article about spiritual teachers being obsessed with worldly things like sex and other egoistic pleasures. What was said was that there is no need to judge them as fraud etc. It is simply that 1st order spiritual pleasures are far more than sex and other egoistic pursuits, so if a person is still obsessed at that level, he probably still needs to progress and is unlikely to have been enlightened. An egoistic soul is like a super interesting rubix cube for a enlightened person to solve.