Reversible plasticity of fear memory-encoding amygdala synaptic circuits even after fear memory consolidation

Ingie Hong, Jihye Kim, Junuk Lee, Sungmo Park, Beomjong Song, Jeongyeon Kim, Bobae An, Kyungjoon Park, Hyun Woo Lee, Seungbok Lee, Hyun Kim, Sang Hyun Park, Khee Dong Eom, Sukwon Lee, Sukwoo Choi

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17 Citations (Scopus)

Abstract

It is generally believed that after memory consolidation, memory-encoding synaptic circuits are persistently modified and become less plastic. This, however, may hinder the remaining capacity of information storage in a given neural circuit. Here we consider the hypothesis that memory-encoding synaptic circuits still retain reversible plasticity even after memory consolidation. To test this, we employed a protocol of auditory fear conditioning which recruited the vast majority of the thalamic input synaptic circuit to the lateral amygdala (T-LA synaptic circuit; a storage site for fear memory) with fear conditioning-induced synaptic plasticity. Subsequently the fear memory-encoding synaptic circuits were challenged with fear extinction and re-conditioning to determine whether these circuits exhibit reversible plasticity. We found that fear memory-encoding T-LA synaptic circuit exhibited dynamic efficacy changes in tight correlation with fear memory strength even after fear memory consolidation. Initial conditioning or re-conditioning brought T-LA synaptic circuit near the ceiling of their modification range (occluding LTP and enhancing depotentiation in brain slices prepared from conditioned or re-conditioned rats), while extinction reversed this change (reinstating LTP and occluding depotentiation in brain slices prepared from extinguished rats). Consistently, fear conditioning-induced synaptic potentiation at T-LA synapses was functionally reversed by extinction and reinstated by subsequent re-conditioning. These results suggest reversible plasticity of fear memory-encoding circuits even after fear memory consolidation. This reversible plasticity of memory-encoding synapses may be involved in updating the contents of original memory even after memory consolidation.

Original languageEnglish
Article numbere24260
JournalPloS one
Volume6
Issue number9
DOIs
Publication statusPublished - 2011 Sep 19

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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    Hong, I., Kim, J., Lee, J., Park, S., Song, B., Kim, J., An, B., Park, K., Lee, H. W., Lee, S., Kim, H., Park, S. H., Eom, K. D., Lee, S., & Choi, S. (2011). Reversible plasticity of fear memory-encoding amygdala synaptic circuits even after fear memory consolidation. PloS one, 6(9), [e24260]. https://doi.org/10.1371/journal.pone.0024260