The brain is an information processing machine, with inputs and outputs.
It really isn't and this method of thinking about the brain isn't helping to figure out how it actually works. This gives a decent overview of why the brain isn't a computer.
When you think about it, our brains evolved over time and so will have been built on top of something approximating simpler organisms around us today, which is to say a purely reactive nervous system like that of a Jellyfish. Add in the fact that sensory deprivation causes us to become unhinged and sensory overload can be quite debilitating as well, we dream when we sleep
So we aren't information processing machines as such, we are of course biological nervous systems and complicated ones at that.