What do grid cells contribute to place cell firing?

Highlights

• •

  It is commonly assumed that grid cell inputs generate hippocampal place fields, but recent empirical evidence brings this assumption into doubt.

• •

  We suggest that place fields are primarily determined by environmental sensory inputs.

• •

  Grid cells provide a complementary path integration input and large-scale spatial metric.

• •

  Place and grid cell representations interact to support accurate coding of large-scale space.

Abstract

The unitary firing fields of hippocampal place cells are commonly assumed to be generated by input from entorhinal grid cell modules with differing spatial scales. Here, we review recent research that brings this assumption into doubt. Instead, we propose that place cell spatial firing patterns are determined by environmental sensory inputs, including those representing the distance and direction to environmental boundaries, while grid cells provide a complementary self-motion related input that contributes to maintaining place cell firing. In this view, grid and place cell firing patterns are not successive stages of a processing hierarchy, but complementary and interacting representations that work in combination to support the reliable coding of large-scale space.