[sa1]

Computers are mathematical concepts, Turing machines being one such concept. Whether computers are implemented using silicon, or oil, or using neurons, it doesn't really matter as we have a mathematical framework for describing abstract machines, and we can determine what is a machine, and what is not.

We did not have this mathematical framework before the age of Turing, Church, Russel, et al.

This doesn't mean that brains are very similar to CPUs, they are not, just like they were not similar to mechanical machines before.

Yet we do now have a way of studying the similarities they have.