The dorsal periacqueductal gray (dPAG) is a midbrain structure having an essential role in coordinating defensive behaviors in response to aversive stimulation. However, the question of whether dPAG neurons can respond to aversive conditioning and retrieval, properties involved in emergence of negative emotional state, is still under debate.

Here we used calcium imaging by fiber photometry to record the activity of dPAG^VGluT2+ and dPAG^GAD2+ neuronal populations during unconditioned and conditioned aversive stimulation. Then, following an unconditioned stimulation we performed a retrieval experiment to quantify memory-like responses of dPAG neurons. This shown that whilst both dPAG^VGluT2+ and dPAG^GAD2+ neuronal populations respond to direct US stimulation, and to CS stimulation during conditioning, only the dPAG^VGluT2+ population persisted in responding to the CS stimulation during retrieval. Finally to better understand these divergences in dPAG^VGluT2+ and dPAG^GAD2+ responses, we investigated their respective connectivity patterns by performing a cell specific monosynaptic retrograde rabies virus tracing experiment. This revealed that different patterns of fibers projects to dPAG^VGluT2+ and dPAG^GAD2+, which could explain part of their response specificities. This may indicate that glutamatergic subpopulation is a main contributor of aversive memories in dPAG.

背周导水管灰色（dPAG）是一种中脑结构，在协调对厌恶刺激的防御行为中具有重要作用。然而，关于dPAG神经元是否能对厌恶性调节和恢复做出反应的问题，涉及负面情绪状态的特性仍在争论中。

在这里，我们通过纤维光度法使用钙成像技术来记录dPAG ^{VGluT2 +}和dPAG ^{GAD2 +}神经元群体在无条件和条件厌恶刺激过程中的活动。然后，在无条件刺激之后，我们进行了检索实验以量化dPAG神经元的记忆样反应。这表明，虽然dPAG ^{VGluT2 +}和dPAG ^{GAD2 +}神经元群体均对直接US刺激和条件刺激期间的CS刺激有反应，但只有dPAG ^{VGluT2 +}群体在取回过程中仍对CS刺激持续存在。最后，以更好地了解dPAG ^{VGluT2 +}和dPAG ^{GAD2 +中的}这些差异响应，我们通过执行细胞特定的单突触逆行狂犬病病毒追踪实验研究了它们各自的连通性模式。这表明纤维的不同模式投射到dPAG ^{VGluT2 +}和dPAG ^{GAD2 +}，这可以解释其部分响应特异性。这可能表明谷氨酸能亚群是dPAG中厌恶记忆的主要贡献者。