I'm currently developing a simulation of the CNS (central nervous system), and from what I've seen so far, I can only say that although neurons themselves are relatively simple cells, a collection of about 100 billion neurons (the Human brain), with around 100 trillion connections between them, is enough to make any person feel desperate when asked to explain the working of it.
No one can explain the working of the brain yet, but through research like that of my own, one day we will.