Recordings show prolonged activity in the visual cortex when looking at images, outlasting conscious awareness of image. More than a quarter of all stroke victims develop a bizarre disorder — they lose conscious awareness of half of all that their eyes perceive.
Long term memories are stored in the hypothalamus as you sleep at night.
Smells are tied to more primitive structures in in the brain. I’m a little rusty on why it makes the memories so strong, but there’s quite a bit of research out on that one.
Trauma is also encoded differently, but there’s a lot of garbage research that muddies the waters on that particular subject.