It’s probably worth mentioning that ALL mini-columns are potentially responsive grid cells. I don’t think that there are any special structures that you could point to and say “those are the grid cells.”
If you look carefully at the Moser video some cells respond when the animal is in certain locations. Not all at once - just one cell assembly when the animal is in a certain location. The “grid” part is that for a given room the responding mini-column fire when the critter is in a certain external locations that we choose to call a grid. Other cells are also responding but they may be reacting to other locations and spacing or other features. Note that there are cells that respond to things like being close to walls or head direction or speed or elapsed time.
This grid pattern resets to a different organization in a different room. This change in the response pattern is called remapping.
The key point that I am making is that in all the mini-columns that could respond - a given mini-column only responds when the critter is in certain places in the room. Other columns respond to other locations in the room and with different spacing between these locations. As you are thinking about “displacement” and shifting activation go look at the Moser video and try to match that up with the theory. The critter comes from different directions and speeds and still builds the activation pattern.
You might say that what goes on in the EC is special for navigation and I will respond with the concept that the same basic computation is being performed all over the cortex. Cortex is cortex. If you wish to assert that there are different computations being performed then I need some reason why they are different.
The Moser video segment starts at 45 seconds into the grid school lesson, note that this is the response of ONE mini-column. The final collection of dots is all the places in the room that the mini-column was firing. If there were more probes in the brain they would be responding to other locations, spacing, and features.
For you visual learners:
