Rapid eye movement (REM) sleep is known to facilitate fear extinction, and REM sleep deprivation after a traumatic event increases the risk of developing post-traumatic stress disorder (PTSD). However, the mechanisms by which REM sleep protects against fearful memories are largely unknown. In a new study published in Current Biology, Hong and colleagues identified the infralimbic cortex (IL) – a brain structure involved in the consolidation of extinction memory – as a critical region for fear extinction during REM in mice. Using calcium imaging, they found that pyramidal neurons in the IL were strongly activated during REM sleep. Optogenetically silencing the activity of these IL pyramidal neurons during REM sleep within 4 h after fear conditioning impaired fear-extinction memory in the animals. These findings further highlight the importance of REM sleep after traumatic events and provides mechanistic insights into the role of REM sleep in fear extinction.

Original reference: Hong, J. et al. Curr. Biol. https://doi.org/10.1016/j.cub.2024.04.018 (2024)

众所周知，快速眼动 (REM) 睡眠有助于消除恐惧，而创伤事件后快速眼动 (REM) 睡眠的剥夺会增加患创伤后应激障碍 (PTSD) 的风险。然而，快速眼动睡眠防止恐惧记忆的机制在很大程度上尚不清楚。在《当代生物学》上发表的一项新研究中，Hong 及其同事发现，边缘下皮层（IL）——一种参与巩固消退记忆的大脑结构——是小鼠快速眼动睡眠期间恐惧消退的关键区域。通过钙成像，他们发现 IL 中的锥体神经元在快速眼动睡眠期间被强烈激活。在恐惧调节后 4 小时内，通过光遗传学方法使这些 IL 锥体神经元在快速眼动睡眠期间的活动沉默，从而损害动物的恐惧消退记忆。这些发现进一步强调了创伤事件后快速眼动睡眠的重要性，并为快速眼动睡眠在恐惧消退中的作用提供了机制见解。

Original reference: Hong, J. et al. Curr. Biol. https://doi.org/10.1016/j.cub.2024.04.018 (2024)