Hi J-p, sorry for the delay!
The functional difference: Place cells typically have one limited place
field (of 10-50% area of a given arena), although some can have a few
fields, but it seems they are not ordered in any way. As the name 'grid
cell' suggests, these have regularly spaced firing fields on a hexagonal
grid (like a crystal structure) with distances of ~30-80 cm. An
individual grid cell has a fixed and highly exact distance between its
firing fields, but the cells on one end of the EC have small distances,
the ones at the other end large distances, and a gradient in between.
The anatomical difference: both cell types live in different areas.
You'll find most place cells in areas CA1 and CA3 of hippocampus
(proper), while gridcells were found in the dorsocauldal part of
entorhinal cortex (EC). It is likely that EC projects on CA1/CA3 and so
grid cells would provide input for place cells.
There's a few more interesting cell types: you don't find place cells in
primates, but instead spatial view cells. Then there are head direction
cells which you might think of as a compass: each cell has a preferred
direction and they fire only when the animal's head is directed there.
Note however, that these ideas are only simplified cartoons of the real
behavior. Specifically, hippocampus is heavily involved in (also
nonspatial) memory.There's lots (1000s) of research papers available
from 30 years of science on these topics. If you want to know more you
might start with Redish's "Beyond the cognitive map". For a few extra
lines see also http://en.wikipedia.org/wiki/Place_cell and
> Hallo Mathias
>> This has nothing to do with your question but as you seem competent in
> this area I wanted to ask you bluntly what the difference between a
> place cell and a grid cell is and how they relate.
> Thank you for your time