What do you perceive as reality?

Just saw Shutter Island, and I should tell you it's the most amazing take on memories and how they define reality and what neuropsychiatry is all about and omg, what not!

SPOILER WARNING: If you've not seen the movie, and are planning to, then don't read ahead.

So, here's where it all matches what ideas I've been having about how the mind works.

Recap: There are only memories. Procedural, declarative, everything. And then, a stimulus appears. It rains, or someone talks, or you fall, or a lion appears behind you. And then, the impulse, the message travels from your sense organ to the brain; it's sorted out and sent to whichever memory/neuron it corresponds to; (again sorted) from there to the procedural memory that it demands; and then to the respective effector organ, and finally you have a response.
[I should tell that I've not yet learned about how this sorting out thing works. I'm assuming it does that, somehow]

So, that's it. The basics.

And then there's this experiment, the split-brain experiment, just google it: Someone has his corpus callosum, the main communication between left and right hemisphere, removed; and he's shown an image to his right eye, say that of ice, and he's shown too many other images to choose from, to associate this ice with, and he chooses a shovel (because you needa shovel the ice). And his left hemisphere is out of the story, it knows nothing about what just happened. And then, the guy is asked why he chose the shovel, while being shown a bird to his left eye. (Should tell you, it's the left hemisphere's Wernicke's area that controls all logic, reasons, etc in most people, sure you've heard that left is rationale and right is creativity). Here's a bird, and here's a question why choose shovel. And suddenly, the left side cooks up a story: "Because birds poop, and you need to clean up that"

Now, that's where Shutter Island comes in. The hero, all he remembers, is from the beginning of the movie, he's in a ship, to shutter island, as a US Marshall. And that's his observation. Now, he's gotta cook up a story consistent with the observations. And he's clever enough to make a perfect one. And there you have! You're insane!

If that didn't make it clear, lemme explain.
Right now, you have all your memories, from your age 5 or 4 (or to be very precise, memories begin forming whenever your nervous system develops, right? Because you do remember the first words you were taught while still struggling on your back) or from the beginning, and then you have a consistent story about the reality out there.

And that reality is based on all your memories. If all of a sudden you were to wake up with none of your memories from the last 2 years, what would you do? How would you feel? If you'd ever fainted for a while you might have experienced this. (Like I fainted, interestingly the first, and as of now the only, time I donated blood, and then I wake up, as people said, 10 seconds later, and all I see is people all around looking at me, and I don't remember what happened, and so instantly, in seconds I am thinking "I've just been in a road accident." And if I was lying down on the road with blood splashed all over my body, I'd just believe that forever. But gladly, I look around and then I remember I was donating blood and the people around, they fill the 10 second void in the memories, and ha! I'm back in my reality.

What if it was not that easy?
What if suddenly somewhere inside your brain, a stroke or something knocks out an year or a decade of your memories and nothing, nobody can explain to you or make you remember everything, everything that happened, to fill in that void?
Suddely your brain, without even letting you* realize it, cooks up a story to fit in all that it remembers and sees. And there you go, you're in a mental asylum which's your home, the psychiatrist is your family friend, and the nurses are your sisters or daughters or servants, and the whole world is crazy!

*Who's this you? Are your brain, your mind and you three different realities?