I love those kinds of videos!
“So trying to imagine now that cortex is this, Sheet of cells, we say it’s six layers, let’s pretend it’s six layers. when it gets, as I said, when it gets to the sort of the end of its sheet, it turns into, it becomes less structured, less uniform. And the first thing, one of the first things it becomes is, literally follow the sheet and it becomes the entorhinal cortex, there’s other things first, but, and one can argue that the entorhinal cortex is, Let’s say roughly three layers thick, and then it continues on and it folds over on top of itself, and the hippocampus is now on top of, it’s folded, like a sheet of paper, and now you have three layers of the hippocampus on top of the three layers of the entorhinal cortex. And this is a very rough approximation, but it’s true. And so the idea there is, one of the ideas that we didn’t come up with, but it seems like it’s a reasonable idea, is that the three layers of the hippocampus on top of the three layers of the entorhinal cortex, then some, at one point in past history, became the six layers of the cortex. And so there’s some analogies between the place cells in the hippocampus being the upper layers of the cortical column and the entorhinal cells and the entorhinal cortex being the lower layers, and I’ve always got that in the back of my mind. So not only did evolution discover this thing, but physically there’s a suggestion that, the cortex became the fusion of these two three layer structures that are aligned on top of one another.” (6’30’’)
Having the six-layered neocortex evolve from the combination of a three-layer entorhinal cortex-like structure and a three-layer hippocampus-like structure sounds like a nice story, but I’m afraid that the 3-layer entorhinal cortex is a wrong assumption. Even if there are significant differences between the mEC and the neocortex, the mEC is often considered to have 6 layers that roughly relate to the 6-layered neocortex (with a tiny L4 and an unclear separation between L5 and L6, in addition to varying cell types like many stellate cells instead of pyramidal cells in superficial layers). Or am I missing something?
Why not try to model the mEC directly as a collection of cortical columns, similar to neocortical areas, using the same framework? Could the entorhinal cortex, thanks to its expressive and meaningful grid cells, serve as the Rosetta stone for deciphering the neocortex?
My previous comment in the other thread is completely related to this video: 2023/01 - A Comprehensive Overview of Monty and the Evidence-Based Learning Module - #5 by mthiboust