Constant Sub-second Cycling between Representations of Possible Futures in the Hippocampus

Cell. 2020 Feb 6;180(3):552-567.e25. doi: 10.1016/j.cell.2020.01.014. Epub 2020 Jan 30.


Cognitive faculties such as imagination, planning, and decision-making entail the ability to represent hypothetical experience. Crucially, animal behavior in natural settings implies that the brain can represent hypothetical future experience not only quickly but also constantly over time, as external events continually unfold. To determine how this is possible, we recorded neural activity in the hippocampus of rats navigating a maze with multiple spatial paths. We found neural activity encoding two possible future scenarios (two upcoming maze paths) in constant alternation at 8 Hz: one scenario per ∼125-ms cycle. Further, we found that the underlying dynamics of cycling (both inter- and intra-cycle dynamics) generalized across qualitatively different representational correlates (location and direction). Notably, cycling occurred across moving behaviors, including during running. These findings identify a general dynamic process capable of quickly and continually representing hypothetical experience, including that of multiple possible futures.

Keywords: CA1; CA2; CA3; decision-making; hippocampus; imagination; place cells; planning; synchrony; theta rhythm.

Publication types

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

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Behavior, Animal / physiology*
  • Cognition / physiology*
  • Decision Making / physiology*
  • Hippocampus / physiology*
  • Locomotion / physiology
  • Male
  • Maze Learning / physiology
  • Nerve Net / physiology
  • Neurons / physiology
  • Rats
  • Rats, Long-Evans
  • Theta Rhythm / physiology