Time cells in the human hippocampus and entorhinal cortex support episodic memory

Proc Natl Acad Sci U S A. 2020 Nov 10;117(45):28463-28474. doi: 10.1073/pnas.2013250117. Epub 2020 Oct 27.


The organization of temporal information is critical for the encoding and retrieval of episodic memories. In the rodent hippocampus and entorhinal cortex, evidence accumulated over the last decade suggests that populations of "time cells" in the hippocampus encode temporal information. We identify time cells in humans using intracranial microelectrode recordings obtained from 27 human epilepsy patients who performed an episodic memory task. We show that time cell activity predicts the temporal organization of retrieved memory items. We also uncover evidence of ramping cell activity in humans, which represents a complementary type of temporal information. These findings establish a cellular mechanism for the representation of temporal information in the human brain needed to form episodic memories.

Keywords: human electrophysiology; medial temporal lobe; theta precession; time cells.

Publication types

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

MeSH terms

  • Behavior Rating Scale
  • Brain
  • Entorhinal Cortex / physiology*
  • Epilepsy
  • Hippocampus / physiology*
  • Humans
  • Memory, Episodic*
  • Temporal Lobe
  • Texas