'heart as physical base' of mental life.
The heart, according to the commentaries as well as to the general Buddhist tradition, forms the physical base (vatthu) of consciousness.
In the canonical texts, however, even in the Abhidhamma Pitaka, no such base is ever localized, a fact which seems to have first been discovered by Shwe Zan Aung (Compendium of Philosophy, pp. 277ff.).
In the Patth. we find repeatedly only the passage: "That material thing based on which mind-element and mind-consciousness element function" (yam rūpam nissāya manodhātu ca mano-viññāna-dhātu ca vattanti, tam rūpam).