Dentate gyrus granule cell firing patterns can induce mossy fiber long-term potentiation in vitro

Rajen Mistry, Siobhan Dennis, Matthew Frerking, Jack R. Mellor

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

Hippocampal granule cells transmit information about behaviorally-relevant stimuli to CA3 pyramidal cells via mossy fiber synapses. These synapses express a form of long-term potentiation (mfLTP) that is non-Hebbian and does not require NMDA receptors. mfLTP is thought to be induced and expressed presynaptically, hence, the major determinant of whether mfLTP occurs is activity in the granule cells. However, it remains unclear whether mfLTP can be induced by activity patterns that granule cells exhibit in vivo, and-if so-what context generates these patterns. To address these issues, we examined granule cell activity from in vivo recordings from rats during performance of a delayed nonmatch-to-sample (DNMS) task and found that granule cells exhibit a wide range of spike patterns. In vitro slice experiments in mice demonstrated that some, but not all, of these patterns of activity could induce mfLTP. By further defining the activity thresholds for mfLTP in hippocampal slices, we found that mfLTP can only be induced by spike patterns that fire in high frequency bursts with a low average firing frequency. Using this information, we then screened for suprathreshold bursts of activity during the DNMS task. In a subset of cells, suprathreshold bursts occurred preferentially during the sampling phase of the task. If suprathreshold bursting took place later, during the delay phase, task performance was disrupted. We conclude that mfLTP can be induced by granule cell spike patterns during a memory task, and that the timing of mfLTP induction can predict task performance.

Original languageEnglish (US)
Pages (from-to)1157-1168
Number of pages12
JournalHippocampus
Volume21
Issue number11
DOIs
StatePublished - Nov 2011

Keywords

  • Delayed nonmatch to sample
  • Electrophysiology
  • Hippocampus
  • LTP
  • Mossy fiber
  • Synaptic plasticity

ASJC Scopus subject areas

  • Cognitive Neuroscience

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