Dorsal CA1 Place Cells in MegaSpace (in progress)

Abstract:

Spatially firing "place cells" within the hippocampal CA1 region form internal maps of the environment necessary for navigation and memory. In rodents, these neurons have been almost exclusively studied in small environments (<4 m2). It remains unclear how place cells encode a very large open 2D environment, which is more analogous to the natural environments experienced by rodents and other mammals. Such an ethologically realistic environment would require a more complex spatial representation, capable of simultaneously representing space at overlapping multiple fine to coarse informational scales. Here we show that in a 'megaspace' (18.6 m2), the majority of dorsal CA1 place cells exhibited multiple place subfields of different sizes, akin to those observed along the septo-temporal axis. Furthermore, the total area covered by the subfields of each cell was not correlated with the number of subfields, and this total area increased with the scale of the environment. The multiple different-sized subfields exhibited by place cells in the megaspace suggest that the ensemble population of subfields form a multi-scale representation of space within the dorsal hippocampus. Our findings point to a new dorsal hippocampus ensemble coding scheme that simultaneously supports navigational processes at both fine- and coarse-grained resolutions.

Full paper can be found here. The SFN2018 poster can be found here. The paper was in Published in Current Biology. There is a preprint on BioArchives.Comments and feedback welcome...

Citation: Dorsal CA1 Hippocampal Place Cells Form a Multi-Scale Representation of Megaspace. Harland B., Contreras M., Souder M. and Fellous JM. Current Biology 31:1–13, 2021.

The Movie can be found here.

• Note: Some of these functions use the excellent Geom2D package from David Legland, available from the Matlab File Exchange repository. Make sure these functions are on your path!

• Figure 2A: Six representative dorsal CA1 place cells recorded first in a small ('regular') environment, then in megaspace, and then back in the same small environment. These cells are stable with a single dominant field in the small environment, but become multi-field/multi-scale in the megaspace.
  • Data
  • Matlab Code
• Figure S3: 14 additional dorsal CA1 cells, from supplemental figure S3 showing a variety of number of subfields, of different sizes (milti-field, multi-scale coding). The track data (path the rat took) and the spikes are included.
  • Data
  • Matlab Code

Notes: Here are pictures and SolidWorks file for the mini-Sphero cart used in the paper: <Files>

Brought to you by the Computational and Experimental Neuroscience Laboratory