The memory for time and space differentially engages the proximal and distal parts of the hippocampal subfields CA1 and CA3

PLoS Biol. 2018 Aug 28;16(8):e2006100. doi: 10.1371/journal.pbio.2006100. eCollection 2018 Aug.

Abstract

A well-accepted model of episodic memory involves the processing of spatial and non-spatial information by segregated pathways and their association within the hippocampus. However, these pathways project to distinct proximodistal levels of the hippocampus. Moreover, spatial and non-spatial subnetworks segregated along this axis have been recently described using memory tasks with either a spatial or a non-spatial salient dimension. Here, we tested whether the concept of segregated subnetworks and the traditional model are reconcilable by studying whether activity within CA1 and CA3 remains segregated when both dimensions are salient, as is the case for episodes. Simultaneously, we investigated whether temporal or spatial information bound to objects recruits similar subnetworks as items or locations per se, respectively. To do so, we studied the correlations between brain activity and spatial and/or temporal discrimination ratios in proximal and distal CA1 and CA3 by detecting Arc RNA in mice. We report a robust proximodistal segregation in CA1 for temporal information processing and in both CA1 and CA3 for spatial information processing. Our results suggest that the traditional model of episodic memory and the concept of segregated networks are reconcilable, to a large extent and put forward distal CA1 as a possible "home" location for time cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CA1 Region, Hippocampal / metabolism
  • CA1 Region, Hippocampal / physiology
  • CA3 Region, Hippocampal / metabolism
  • CA3 Region, Hippocampal / physiology
  • Hippocampus / metabolism*
  • Hippocampus / physiology
  • Male
  • Memory / physiology*
  • Mice
  • Mice, Inbred C57BL
  • Spatial Processing / physiology*
  • Temporal Lobe

Grants and funding

The Mercator Stiftung. Received by MMS. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The SonderForschungBereich 779 (B17). Received by MMS. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The State of Saxon Anhalt, the Exzellenzmittel (grant number MW-21LMSP6). Received by HJH. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.