When you change your personality (for a variety of reasons, damage, drugs - whatever) you will still see the world through the eyes of that very same body - even though the body has replaced all the atoms over many years.
I find that a very weird thing. If consciousness is locked to your brain, it should fade away as the chemicals and other components of your brain gets replaced and changing over time. At the very least, you should not be able to see the world through your eyes or hear sounds through your ears. You should either stop experiencing the world from your local perspective, because the local perspective is ever-changing - or die (from your perspective), even if your body and brain keeps living. In some way or the other, "you" cease to exist when your components make even the slightest of changes.
Yet even if you get dementia or serious brain damage, you still see the world through that very same body even if you're not thinking the same thoughts or hold the same ideas/opinions/beliefs as before.
Let's come up with another thought-experiment:
Suppose we make an EXACT copy of you. Then we freeze the original you and put you unconscious (probably best the other way around

Then we kill the original, and put the copy into life. What "you" should experience is a "flicker" or "lag" in your experience similar to a broken movie where you have one situation with A->B->C=D (current), but instead you experience something like: A->B = V - making no coherent connections to what just happened, like a broken movie that suddenly jumps to another scenery/situation (or even movie) as the conscious parts gets in an entirely different location. Like opening the door in your house in whever you live, expecting to see your neighbors house, instead you end up somewhere else entirely.
But I bet you won't. Because what if we keep the original alive while we awake the copy? Which body will "you" see through? The original, of course. At least that's what our experiences so far tells us.
Therefore the conclusion must be one of the two of the following:
The consciousness is originating deep inside the brain in some "core atoms" or "core molecules" that will never get replaced or change and which will experience black/darkness upon death of the brain. In that case, the "soul" can be said to be physically real and exists in some part deep inside the brain, it will then be measureable.
The problem with this idea is that atoms decay. So do all atoms, they emit energy (light) and therefore your consciousness should fade away over time.
But it doesn't.
OR
The core of the Consciousness is not really inside the brain but in some other dimension or reality or source. It should then be illustrated like the roots of a tree pointing the same way to a core source, and as you climb up the tree you see various branches (various conscious beings). Like a "brain in the vat"-scenario, just without the brain but only the consciousness. In other words, we exist in some other dimension, equivalent to watching a movie unfolding before our eyes with Virtual Reality.