Effect of Ablated Hippocampal Neurogenesis on the Formation and Extinction of Contextual Fear Memory

Mol Brain. 2009 Jan 13;2:1. doi: 10.1186/1756-6606-2-1.


Newborn neurons in the subgranular zone (SGZ) of the hippocampus incorporate into the dentate gyrus and mature. Numerous studies have focused on hippocampal neurogenesis because of its importance in learning and memory. However, it is largely unknown whether hippocampal neurogenesis is involved in memory extinction per se. Here, we sought to examine the possibility that hippocampal neurogenesis may play a critical role in the formation and extinction of hippocampus-dependent contextual fear memory. By methylazoxymethanol acetate (MAM) or gamma-ray irradiation, hippocampal neurogenesis was impaired in adult mice. Under our experimental conditions, only a severe impairment of hippocampal neurogenesis inhibited the formation of contextual fear memory. However, the extinction of contextual fear memory was not affected. These results suggest that although adult newborn neurons contribute to contextual fear memory, they may not be involved in the extinction or erasure of hippocampus-dependent contextual fear memory.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ablation Techniques*
  • Animals
  • Bromodeoxyuridine / metabolism
  • Cell Count
  • Conditioning, Psychological
  • Extinction, Psychological* / drug effects
  • Extinction, Psychological* / radiation effects
  • Fear / drug effects
  • Fear / physiology*
  • Fear / radiation effects
  • Gamma Rays
  • Hippocampus / anatomy & histology
  • Hippocampus / drug effects
  • Hippocampus / radiation effects
  • Hippocampus / surgery*
  • Male
  • Memory / drug effects
  • Memory / physiology*
  • Memory / radiation effects
  • Methylazoxymethanol Acetate / pharmacology
  • Mice
  • Mice, Inbred C57BL
  • Motor Activity / drug effects
  • Motor Activity / radiation effects
  • Neurogenesis / drug effects
  • Neurogenesis / physiology*
  • Neurogenesis / radiation effects
  • Time Factors


  • Methylazoxymethanol Acetate
  • Bromodeoxyuridine