Heart base - or brain

And as I said in the next sentence,
“All of us are much conditioned by an age where scientific discoveries seem so testable and provable. It is natural that doubts arise on this matter”.

Is this pain signal mentality or materiality? Do you agree with the quote from the Commentary: > (Nidaanavagga) VII The Great Subchapter 61

(1) Uninstructed (1) p. 595 Samyutta Nikaya Vol 1 (translated by Bhikkhu Bodhi) "
note 157: Spk: one citta is
not able to endure for a whole day or a whole night. Even in the
time of a fingersnap many hundred thousand kotis of cittas arise and
cease (1 koti=10 million).

There are many conditions needed for a moment of kaya viññāṇa (bodily consciousness). It is similar to seeing - without light visible objects cannot appear. Or if the eyebase is impaired for some reason even briefly then visible object won’t appear. Similarly if the kayavatthu is impaired then no body consciousness can arise at the area where it is impaired (for example if a limb is paralysed or if someone was under anesthetic).
Without understanding Dhamma we would always think that “I” am looking at this or that but the commentary to the Sammanaphala sutta (The Fruits of Recluseship, Bhikkhu Bodhi), talking about looking ahead or looking aside, breaks this down into various conditions as explained in the Patthana.

The eye is a support condition: forms are an object condition; adverting is a proximity, contiguity, decisive support, absence, and disappearance condition; light is a decisive support condition; feeling etc are conascence conditions. Thus looking ahead and looking aside are discerned in the assemblage of these conditions.

And also for kaya viññāṇa (bodily consciousness) there is the incredibly brief meeting of the tangible data base (hardness, heat etc) , the kayavatthu (body base) and the kaya viññāṇa.

Vism. XVII
85. The tangible-data base is a condition, as prenascence condition, for the body-consciousness element and for the states associated therewith..[..]

And other conditions are involved: the body-base (kāyavatthu) is the support condition; tangible datum (phoṭṭhabba—hard/soft, hot/cold, pressure/motion) is the object condition; adverting (āvajjana) functions as proximity, contiguity, decisive-support, absence, and disappearance conditions; the earth element (paṭhavī-dhātu, i.e., ‘solidity/extension’) is a decisive-support (upaniṣsaya) for the arising; and the co-arisen mental factors—feeling, perception, volition, etc.—are conascent (sahajāta) . And these are present for the brief meeting and then immediately cease and new conditions arise.

What is the purpose of defining all these conditions?: It is a step in learning that there are only these conditioned elements, no self.
As the Tika to the Sammanaphala sutta says:

Looking ahead and looking aside being discerned by way
of the five aggregates, who is it, separate from those aggregates, that looks ahead? Who looks aside? The meaning is: there is no one who looks ahead, no one who looks aside p.118 of Bodhi translation

Thus there is benefit in seeing life through this lens, to see that there is only mentality - materiality. We may be satisfied with what we learn from science but unless there is the development of understanding of what is really present we remain anchored to the conceptual world with all its assumptions.