Subicular activation preceding hippocampal ripples in vitro

Sci Rep. 2013;3:2696. doi: 10.1038/srep02696.

Abstract

Sharp wave-ripple complexes (SW-Rs), a transient form of high-frequency field oscillations observed in the hippocampus, are thought to mediate memory consolidation. They are initiated mainly in hippocampal CA3 area and propagate to the entorhinal cortex through the subiculum; however, little is known about how SW-Rs are initiated and propagate. Here, we used functional multineuronal calcium imaging to monitor SW-R-relevant neuronal activity from the subiculum at single-cell resolution. An unexpected finding was that a subset of subicular neurons was activated immediately before hippocampal SW-Rs. The SW-R-preceding activity was not abolished by surgical lesion of the CA1-to-subiculum projection, and thus, it probably arose from entorhinal inputs. Therefore, SW-Rs are likely to be triggered by entorhinal-to-CA3/CA1 inputs. Moreover, the subiculum is not merely a passive intermediate region that SW-Rs pass through, but rather, it seems to contribute to an active modification of neural information related to SW-Rs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Animals
  • CA1 Region, Hippocampal / physiology
  • Calcium / metabolism
  • Entorhinal Cortex / physiology*
  • Hippocampus / physiology*
  • Male
  • Mice
  • Neurons / physiology
  • Optical Imaging / methods

Substances

  • Calcium