前边缘皮层稳定与动态神经元集群共同编码习得性威胁价值，支撑泛化与辨别
Complementary stable and dynamic prelimbic ensembles encode learned threat value underlying generalization and discrimination
前边缘皮层（PL）在神经元集群大幅更替的情况下仍维持稳定的威胁价值编码。研究用自由活动小鼠的纵向钙成像追踪 PL 活动 30 天，覆盖听觉辨别性恐惧学习与提取全过程。广义线性模型显示，音调威胁价值比冻结行为更能解释梯度化活动，提示 PL 主要编码刺激显著性。群体相似性在电击关联音调与高度泛化音调上最高，稳定神经元跨 session 保留梯度，而学习调节动态频率选择神经元的比例。两类集群共同在持续重组中实现稳定的威胁价值编码。
来源：eLife · doi.org
Adaptive behavior requires assigning emotional value to sensory cues and generalizing to similar stimuli. The prelimbic cortex (PL) is critical for threat expression and discrimination, yet its neuronal ensembles undergo substantial turnover over time. How stable population codes emerge despite this reorganization remains unknown. Using longitudinal calcium imaging in freely moving mice, we tracked PL activity for 30 days during auditory discriminative fear learning and retrieval. Despite substantial ensemble turnover, stable graded representations persisted in PL populations. A generalized linear model showed that the tone threat value explained graded activity better than freezing, indicating that PL primarily encodes stimulus significance. Population similarity across stimulus presentations was highest for shock-associated and highly generalized tones, suggesting a stable population code underlying threat generalization. Stable neurons preserved graded gradients across sessions, whereas learning modulated the rate of dynamic frequency-selective neurons. Together, these populations enabled stable threat-value coding despite ongoing ensemble reorganization.