How grid cell neurons encode rat position
Speaker: Ted Brookings , University of California, Santa Barbara
Date: February 16 2007
Time: 2:00PM to 3:00PM
Location: 32-D507
Host: Polina Golland, CSAIL
Contact: Polina Golland, x38005, polina@csail.mit.edu
Recently it was discovered that neurons in an area of the cortex (called
dMEC) of rats, fire on every vertex of a regular triangular lattice that
tiles 2-d space. These so-called "grid cells" efficiently encode rat
position in a system that can be shown is analogous to a residue number
system (RNS). By interpreting measured dMEC properties within an RNS
framework, we can estimate the amount of position information stored
within dMEC, and show how an RNS-like scheme is particularly well-suited
to store and update positional information. We also describe
limitations on navigational schemes employing this information. Noise
and systematic errors in grid cell firing provide a serious challenge to
any RNS-like scheme, and the need for robust "read out" of information
places lower bounds on the number of grid cells required, and constrains
how encoded information can be used. Considering these limitations as
well as existing information on the connectivity of dMEC and the
hippocampus, we suggest a simple model of how grid cell information is used.
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