The hippocampal engram maps experience but not place

Kazumasa Tanaka, Hongshen He, Anupratap Tomar, Kazue Nisato, Arthur Huang, Thomas J McHugh

Research output: Contribution to journalArticle (Academic Journal)peer-review

68 Citations (Scopus)
461 Downloads (Pure)


Episodic memories are encoded by a sparse population of hippocampal neurons. In mice, optogenetic manipulation of this memory engram established that these neurons are indispensable and inducing for memory recall. However, little is known about their in vivo activity or precise role in memory. We found that during memory encoding, only a fraction of CA1 place cells function as engram neurons, distinguished by firing repetitive bursts paced at the theta frequency. During memory recall, these neurons remained highly context specific, yet demonstrated preferential remapping of their place fields. These data demonstrate a dissociation of precise spatial coding and contextual indexing by distinct hippocampal ensembles and suggest that the hippocampal engram serves as an index of memory content.

Original languageEnglish
Pages (from-to)392-397
Number of pages6
Issue number6400
Early online date27 Jul 2018
Publication statusE-pub ahead of print - 27 Jul 2018


  • engrams
  • place cells
  • Hippocampus
  • memory Indexing


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