Hippocampal "time cells": time versus path integration

Neuron. 2013 Jun 19;78(6):1090-101. doi: 10.1016/j.neuron.2013.04.015. Epub 2013 May 23.


Recent studies have reported the existence of hippocampal "time cells," neurons that fire at particular moments during periods when behavior and location are relatively constant. However, an alternative explanation of apparent time coding is that hippocampal neurons "path integrate" to encode the distance an animal has traveled. Here, we examined hippocampal neuronal firing patterns as rats ran in place on a treadmill, thus "clamping" behavior and location, while we varied the treadmill speed to distinguish time elapsed from distance traveled. Hippocampal neurons were strongly influenced by time and distance, and less so by minor variations in location. Furthermore, the activity of different neurons reflected integration over time and distance to varying extents, with most neurons strongly influenced by both factors and some significantly influenced by only time or distance. Thus, hippocampal neuronal networks captured both the organization of time and distance in a situation where these dimensions dominated an ongoing experience.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Hippocampus / cytology*
  • Hippocampus / physiology*
  • Male
  • Maze Learning / physiology*
  • Motor Activity / physiology*
  • Neural Pathways / cytology
  • Neural Pathways / physiology
  • Rats
  • Rats, Long-Evans
  • Space Perception / physiology*
  • Time Factors