Zotaster; interesting. A couple of things.

Firstly, you say that a turing machine should be able to simulate a brain... maybe. But there are some things which are mathematically impossible for a turing machine to do.

Secondly, obviously there's nothing intrinsically 'conscious' about neurons, they're blobs of water and protein and ions. The nervous system could just as well have evolved to be made of something else entirely. This is why I consider functionalism to be such a strong argument, there's no way around it. What's so special about a turing machine that makes it not conscious?

Then again, the functionalism approach has some paradoxes of its own. These are made clear when you consider the 'conversation with Einstein's brain' analogy, where a book of instructions of how to emulate Einstein's brain is written. Are we to believe that using this book creates consciousness? What if lots of people read it at the same time? What if they only read little bits? Or read it wrong? Or read it backwards? Have you got little bits of consciousness popping into existence and doing all kinds of bizarre things?