Mammalian grid cells discharge when an animal crosses the points of an imaginary hexagonal grid tessellating the environment. I will show how animals can navigate by reading out a population vector of such activity patterns across multiple spatial scales. The theory explains key experimental results about grid cells, makes testable predictions for future physiological and behavioural experiments, and provides a mathematical foundation for the concept of a “neural metric” for space. For goal-directed navigation, the proposed allocentric grid cell representation can be readily transformed into the egocentric goal coordinates needed for planning movements.

This talk is based on a paper by Martin Stemmler, Alexander Mathis and myself (advances.sciencemag.org/content/1/11/e1500816).