nothing happens to them. actually. it’s not like there’s decay where the rest is jelly and just the oldest root is vital under a melted mass. we’re so used to thinking of everything in terms of rootrot and decay but that’s not how it is. no, actually the whole thing is still intact. except for a sort of plaque that forms on the surface. a kind of crystal covering which solidifies over most parts and then it doesn’t allow the brain to work.
it’s in one piece underneath this crystal but then functionally something is in the way and it prevents them from forming new memories, or from accessing many of the older ones. like the calcified flakes inside a kettle that hasn’t been cleaned, it’s something preexisting in the water itself which given time wants to solidify.
you can hear it if you swirl the few droplets of water around the kettle, it sounds like it’s full of chipped glass. but it’s just something that comes from the liquid itself. no, not even something distilled from out of the steel. the water itself is full of microscopic solid parts and these eventually find each other.
it’s like that.
they did a trial in mice with a certain wavelength of light. it loosened the plaque and the mice were able to remember their way through the mazes. they could even complete new mazes. of course, they say that 98% of research with mice never translates to humans. but in theory you could take a certain wavelength of light which you would generate with cheap LEDs and this would be enough to loosen the crystal.
