Top-down effects in the brain.

The purpose of this investigation is to demonstrate that one is unable to understand the operation of the brain without taking top-down effects into account. This is demonstrated by looking in turn at evolutionary and developmental aspects, then at functional aspects related to sensory systems, learning processes, and motor processes that lead to action on the world. It is also clear in terms of the effects of a society on brains located in that society. The possibility of top down affects exists both because of multiple realisability of higher level processes at lower levels, and because lower level elements are adapted to perform their higher level functions. These top-down processes validate a non-reductionist approach to how the brain works.