Dendritic spikes in hippocampal granule cells are necessary for long-term potentiation at the perforant path synapse

Elife. 2018 Mar 26:7:e35269. doi: 10.7554/eLife.35269.

Abstract

Long-term potentiation (LTP) of synaptic responses is essential for hippocampal memory function. Perforant-path (PP) synapses on hippocampal granule cells (GCs) contribute to the formation of associative memories, which are considered the cellular correlates of memory engrams. However, the mechanisms of LTP at these synapses are not well understood. Due to sparse firing activity and the voltage attenuation in their dendrites, it remains unclear how associative LTP at distal synapses occurs. Here, we show that NMDA receptor-dependent LTP can be induced at PP-GC synapses without backpropagating action potentials (bAPs) in acute rat brain slices. Dendritic recordings reveal substantial attenuation of bAPs as well as local dendritic Na+ spike generation during PP-GC input. Inhibition of dendritic Na+ spikes impairs LTP induction at PP-GC synapse. These data suggest that dendritic spikes may constitute a key cellular mechanism for memory formation in the dentate gyrus.

Keywords: action potential backpropagation; active dendrites; dendritic spike; dentate gyrus granule cell; long-term potentiation; neuroscience; perforant-path synapse; rat.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials*
  • Animals
  • Hippocampus / physiology*
  • Long-Term Potentiation*
  • Memory*
  • Models, Neurological
  • Perforant Pathway / physiology*
  • Rats
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Synapses / physiology*

Substances

  • Receptors, N-Methyl-D-Aspartate

Grants and funding

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.