Your Cortex Contains 17 Billion Computers

Neural networks of neural networks

Credit: brentsview under CC BY-NC 2.0
Brains receive input from the outside world, their neurons do
 something to that input, and create an output. That output
may be a thought (I want curry for dinner); it may be an action
(make curry); it may be a change in mood (yay curry!).
Whatever the output, that “something” is a transformation of
some form of input (a menu) to output (“chicken dansak, please”).
And if we think of a brain as a device that transforms inputs to
outputs then, inexorably, the computer becomes our analogy of
choice.