A consciousness isn't just action/reaction to stimulus. Consciousness is an awareness, or understanding of the action/reaction, per se. For instance. When I'm looking at the computer screen, I'm actually looking at the computer screen. I'm conscious of it. However, a robot could look at the computer screen and react to stimulus, but still not be conscious.
I think this sums it up pretty well.
http://dictionary.reference.com/browse/consciousI don't get why you disagree that the brain is what causes consciousness. You'll listen to whatever scientists tell you, except that.