Afterlife?

I've been thinking a lot lately, since there's been nothing much to do around here the day before school starts apart from feel guilty about undone work. I thought to myself for the millionth time (I'm sure I'm not alone in thinking about this): what happens when someone dies?
And for the first time something dawned on me. What if our consciousness to the "world of the living", for lack of better words, is only present when our brain is fully functioning? What if once the brain dies, the consciousness lives on, but it is cut off from the world we know because it relies on the brain as an interface that links it with this world? Would thoughts and feelings remain the same, or would the whole science of existing completely change? If they stayed the same, would one mind of a dead being link to another?
A sort of proof of this theory is that when people have brain injuries, their personality appears to have changed. Maybe it is not that the personality has gone, or been replaced, but that the person is not able to show this characteristic, or deal with certain feelings like anger, because the part of the brain that links that characteristic with this world is damaged.
Another thing I wondered was how far down the food chain it would go (if this was the case), because an ant, for example, as far as we know doesn't have a conscience as it is not developed enough. So what would be there to live on? Perhaps for one's consciousness to carry on, one needs to have enough of a consciousness to think for one's self. So would, for instance, a dog live on? Or would it just be humans who's minds are complex and individual enough to have a real idea of what is going on? It is possible that everything lives on, but some are aware of it and some are not.
It is of course possible that none of these things are true, and that as a matter of fact nothing happens when someone dies.
I would like to make it clear to anyone religious who has read this entry that I do believe that it is also possible for there to be a supreme being who created everything and therefore destroys everything and keeps it in another place seperate to our world, and I did not intend to offend anyone by posting my ideas about afterlife. It is just my point of view, and I'm not claiming that I am right in any way - everyone has a right to their own beliefs and opinions.