Random thought: assuming grid cell firing is based on integration of sensory input, I wonder if that’s why most sensors are “mounted” on the head: to conserve training of grid cells?
Are there any animals with high power senses not mounted on the head, are there different populations of grid cells for that non-head sense? Do animals with very inflexible necks have different place cell circuitry?
Or perhaps more directly, are the populations of touch sensor grid cells different than sight, sound? Is their transform circuitry different, e.g. bypassing head position integration?