[Neuroscience] Re: Looking for rat trajectories

Mathias via neur-sci%40net.bio.net (by mathiasDOTfranzius from webDELETEME.de)
Mon Mar 12 05:21:56 EST 2007

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 


J-P wrote:
> 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
> J-P

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