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.
- Sooyun Kim
- Sooyun Kim
- Won-Kyung Ho
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the Seoul National University. All of the animals were handled according to approved institutional animal care and use committee (IACUC) of the Seoul National University. The protocol (Approval #: SNU-090115-7) was approved by the Committee on the Ethics of Animal Experiments of the Seoul National University. Animals were anesthetized by inhalation of 5% isoflurane before sacrifice, and every effort was made to minimize suffering.
- John Huguenard, Stanford University School of Medicine, United States
© 2018, Kim et al.
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