Correlations and functional connections in a population of grid cells

PLoS Comput Biol. 2015 Feb 25;11(2):e1004052. doi: 10.1371/journal.pcbi.1004052. eCollection 2015 Feb.

Abstract

We study the statistics of spike trains of simultaneously recorded grid cells in freely behaving rats. We evaluate pairwise correlations between these cells and, using a maximum entropy kinetic pairwise model (kinetic Ising model), study their functional connectivity. Even when we account for the covariations in firing rates due to overlapping fields, both the pairwise correlations and functional connections decay as a function of the shortest distance between the vertices of the spatial firing pattern of pairs of grid cells, i.e. their phase difference. They take positive values between cells with nearby phases and approach zero or negative values for larger phase differences. We find similar results also when, in addition to correlations due to overlapping fields, we account for correlations due to theta oscillations and head directional inputs. The inferred connections between neurons in the same module and those from different modules can be both negative and positive, with a mean close to zero, but with the strongest inferred connections found between cells of the same module. Taken together, our results suggest that grid cells in the same module do indeed form a local network of interconnected neurons with a functional connectivity that supports a role for attractor dynamics in the generation of grid pattern.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Animals
  • Entorhinal Cortex / cytology*
  • Male
  • Models, Neurological*
  • Models, Statistical
  • Nerve Net / physiology*
  • Neurons / physiology*
  • Rats
  • Rats, Long-Evans

Grant support

Funding was provided by the Kavli Foundation, Norwegian Research Council center of Excellence grant and EU ITN Network Across Disciplines. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript