Where is Consciousness?

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The brain is a very complex network that just works for most of us, but why and how? How and where does consciousness come from? Our brains work without us being aware of their functions and we go about life not really knowing about how our conscious are formed.

Professor Marcus du Sautoy goes about to figure out where our consciousness comes from. He does and dissects a brain to show us exactly what is happening. He concludes that consciousness comes from the brain stem, in a system called the Reticular Activating System. This system sends projections to the thalamus that then send them out to everywhere. These projections activate the cortex and allow us to be conscious. This documentary concluded that the key to consciousness was activation and whenever an activation occurs, you are being conscious of your surroundings.

I think it is amazing that people are aware because of one part of the brain, rather than prior being told that our consciousness is just there. Now I know the exact cause and how
. The instant thought that comes to my mind, though, is how can they tell for sure that this is what creates consciousness. It is something that you really cannot test and I am wondering how they came up with their explanations of consciousness.