Stress enhances fear by forming new synapses with greater capacity for long-term potentiation in the amygdala

Aparna Suvrathan, Sharath Bennur, Supriya Ghosh, Anupratap Tomar, Shobha Anilkumar, Sumantra Chattarji*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

60 Citations (Scopus)

Abstract

Prolonged and severe stress leads to cognitive deficits, but facilitates emotional behaviour. Little is known about the synaptic basis for this contrast. Here, we report that in rats subjected to chronic immobilization stress, long-term potentiation (LTP) and NMDA receptor (NMDAR)-mediated synaptic responses are enhanced in principal neurons of the lateral amygdala, a brain area involved in fear memory formation. This is accompanied by electrophysiological and morphological changes consistent with the formation of 'silent synapses', containing onlyNMDARs. In parallel, chronic stress also reduces synaptic inhibition. Together, these synaptic changes would enable amygdalar neurons to undergo further experience-dependent modifications, leading to stronger fear memories. Consistent with this prediction, stressed animals exhibit enhanced conditioned fear. Hence, stress may leave its mark in the amygdala by generating new synapses with greater capacity for plasticity, thereby creating an ideal neuronal substrate for affective disorders. These findings also highlight the unique features of stress-induced plasticity in the amygdala that are strikingly different from the stress-induced impairment of structure and function in the hippocampus.

Original languageEnglish
Article number20130151
JournalPhilosophical Transactions B: Biological Sciences
Volume369
Issue number1633
DOIs
Publication statusPublished - 5 Jan 2014

Keywords

  • Dendritic spines
  • Emotion
  • Long-term potentiation
  • Neural plasticity
  • NMDA receptors
  • Silent synapses

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