The fact remains, however, that our understanding of how the brain works is about where medicine was at the turn of the century, 100 years ago. Researchers still don't understand the most basic mechanisms of how things like electrical impulses and neurochemical changes work to affect changes. It's like when doctors observed that cleaning out a wound will help your survival rate, but not understanding anything about infection or how infection causes harm.

So these distinctions -- "neurological vs. something else" -- are, I would argue, arbitrary and not really helpful at this stage. You can't get a blood test that shows you have "depression," and, in fact, all mental illnesses are diagnosed still through behavioral symptoms -- you tell me what's wrong, and I see what category that best fits into.

That's not to say it will always be this way. A decade or two from now, who knows?

And remember -- everything you do affects your brain chemistry. When you're happy, I can you show you PET scans of how your happiness lights up parts of your brain. When you're sad, same thing. When you're bored, same thing. When you're having a heated argument, or playing a video game, same thing. So the fact that we can show some brains light up differently than others is a good start, but it doesn't help us at all to establish ontology.

John