Electronic computers, artificial neural networks, hydraulic machines, clockworks etc... are all computationally equivalent to the brain. Anyone making such comparisons is grasping at the fact that the brain can be understood computationally. To complain that there are no pressure-driven pistons, rotating gears or whatever in the brain is missing the point of the analogy, IMHO, which is: all these systems perform computation on top of a physical substrate, and what we actually (should) care about is the computation itself and not the mechanical workings of the substrate.