Please tell me why my question was closed:
It is obvious that the question is completely concrete (at least in the part of pain) and falls in the topic of metaphysics.
On a neurological forum this would be of course off-topic because the question asks for an answer for any poissible brain construction, not only that based on neurons.
Also as I can tell, theoretical neurology leaves the question about what creatures can experience pain (and qualia in general) to philosophy.
Please re-open this question, I see nothing wrong with it. If it is not suitable for this site then this site is not about philosophy at all.