Cell Biology and Neurobiology Institute, National Research Council of Italy, Rome, Italy.
Learn Mem. 2011 Aug 15;18(9):554-7. doi: 10.1101/lm.2246711. Print 2011.
Structural synaptic changes occur in medial prefrontal cortex circuits during remote memory formation. Whether extinction reverts or further reshapes these circuits is, however, unknown. Here we show that the number and the size of spines were enhanced in anterior cingulate (aCC) and infralimbic (ILC) cortices 36 d following contextual fear conditioning. Upon extinction, aCC spine density returned to baseline, but the enhanced proportion of large spines did not. Differently, ILC spine density remained elevated, but the size of spines decreased dramatically. Thus, extinction partially erases the remote memory network, suggesting that the preserved network properties might sustain reactivation of extinguished conditioned fear.
在远距离记忆形成过程中，内侧前额叶皮层回路发生结构突触变化。然而，尚不清楚消退是恢复还是进一步重塑这些回路。在这里，我们发现，在进行情境性恐惧条件反射 36 天后，扣带前回（aCC）和下边缘回（ILC）皮质中的棘突数量和大小增加。在消退时，aCC 的棘突密度恢复到基线，但大棘突的比例没有增加。相反，ILC 的棘突密度仍然升高，但棘突的大小显著减小。因此，消退部分抹去了远距离记忆网络，这表明保留的网络特性可能维持已消除的条件性恐惧的重新激活。
