Reversible Plasticity of Fear Memory-Encoding Amygdala Synaptic Circuits Even after Fear Memory ConsolidationReportar como inadecuado




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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.



Autor: Ingie Hong, Jihye Kim, Junuk Lee, Sungmo Park, Beomjong Song, Jeongyeon Kim, Bobae An, Kyungjoon Park, Hyun Woo Lee, Seungbok Lee

Fuente: http://plos.srce.hr/



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