Hippocampal neurogenesis and forgetting

Trends Neurosci. 2013 Sep;36(9):497-503. doi: 10.1016/j.tins.2013.05.002. Epub 2013 Jun 12.


The hippocampus is thought to automatically encode all experience, yet the vast majority of our experiences are not remembered later. Although psychological theories have postulated the existence of decay processes for declarative memory, the corresponding neurobiological mechanisms are unknown. Here we develop the hypothesis that ongoing hippocampal neurogenesis represents a decay process that continually clears memories from the hippocampus. As newborn granule cells integrate into established hippocampal circuits, they form new input and output connections over the course of several weeks. Because successful memory retrieval relies on reinvoking patterns of activity that occurred at the time of encoding (pattern completion), neurogenesis-induced remodeling of hippocampal circuits incrementally reduces the likelihood that a given retrieval cue will reinvoke a previously stored pattern.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Hippocampus / cytology*
  • Hippocampus / physiology*
  • Humans
  • Mental Disorders / pathology*
  • Neurogenesis / physiology*
  • Neurons / physiology*