Early life stress, neuron-type function and a raphe-amygdala circuit for threat estimation

项目摘要。早期生活压力(ELS)对成年后的心理健康有深远的负面影响。 扰乱用于威胁评估的神经回路。这一提议旨在检验一个重要的假设，即 ELS重新编程DR-γ-氨基丁酸(GABA)、5-羟色胺(5-HT)和非-GABA-非-5-HT的信号 神经元夸大血乳酸威胁估计并夸大恐惧。具体地说，DR5HT神经元和GABA神经元 对威胁性提示做出反应，而非GABA-非5HT神经元对令人惊讶的遗漏做出反应 的结果，称为负预测误差(-PE)。ELS通过减少GABA来重新编程DR 抑制5-羟色胺，同时减少非-GABA-非-5-羟色胺输出。ELS在DR上的最终结果 功能是增加5-羟色胺的输出，以夸大血乳酸威胁估计和夸大恐惧。我们设计了一个 ELS程序，青春期前的大鼠经历多种类型的物理应激源。成年后， 准确的威胁估计使用恐惧辨别范例进行评估，在该范例中，三个线索发出不同的信号 脚部电击的概率：危险(p=1.00)、不确定性(p=0.25)和安全(p=0.00)。在目标1中，我们将记录 正常或ELS大鼠在恐惧辨别过程中DR和BLA的单位活动，DR- 5HT神经元缺失或DR-GABA神经元缺失。神经元类型删除将通过使用特定的 转基因大鼠品系(GAD-cre或Tph2-cre)与cre依赖的caspase结合。初步分析将 关注提示期和提示期后的神经活动，提示期是生成威胁估计的时期 -PE被生成并将直接决定ELS和神经元类型缺失对单个单元的影响 活动。在目标2中，我们将在提示期间使用光遗传抑制，当威胁估计为 生成，以及提示后时间段，当生成-PE时，以演示GABA博士、DR 5羟色胺、DR非5羟色胺人群，以及对不确定的恐惧中DR到BLA的预测。这将揭示因果关系 对于DR神经元类型，以及直接DR到BLA的预测，在正常和ELS中进行准确的威胁估计 个人。在目标3中，我们将结合神经元类型特异性的DR的光发生激发和单个单位 ELS大鼠血乳酸的记录。在提示期间，DR GABA神经元将被刺激，而DR非5HT 在-PE期间，神经元将受到刺激，以恢复适当的恐惧和BLA神经活动，以 不确定性。这项提议将证明ELS重新编程DR中神经元类型特定的信号。 BLA电路，以夸大威胁估计。这一结果将揭示药物治疗恢复的新靶点 ELS个体的准确估计。这项研究的长期目标是绘制一个完整的神经 准确的威胁评估，揭示ELS如何扰乱电路功能，并利用这些知识进行全面设计 有效的治疗方法，以恢复受ELS影响的个人的准确威胁估计。

Project Summary. Early life stress (ELS) profoundly and negatively affects mental health into adulthood, disrupting neural circuits for threat estimation. This proposal is designed to test the overarching hypothesis that ELS reprograms signaling of DR gamma-aminobutyric acid (GABA), serotonin (5HT), and non-GABA-non-5HT neurons to inflate BLA threat estimates and exaggerate fear. Specifically, DR 5HT neurons and GABA neurons are responsive to threatening cues, while non-GABA-non-5HT neurons are responsive to surprising omission of aversive outcomes, termed a negative prediction error (–PE). ELS reprograms DR by diminishing GABA inhibition of 5HT, while concurrently diminishing non-GABA-non-5HT output. The net result of ELS on DR function is to increase 5HT output to inflate BLA threat estimation and exaggerate fear. We have designed an ELS procedure in which pre-pubertal rats experience multiple categories of physical stressors. In adulthood, accurate threat estimation is assessed with a fear discrimination paradigm in which three cues signal different probabilities of foot shock: danger (p=1.00), uncertainty (p=0.25), and safety (p=0.00). In Aim 1, we will record single-unit activity from the DR and BLA during fear discrimination in normal or ELS rats with DR intact, DR- 5HT neuron deletion or DR-GABA neuron deletion. Neuron-type deletion will be achieved by using specific transgenic rat lines (GAD-cre or TPH2-cre) in combination with cre-dependent caspases. Primary analyses will focus on neural activity during the cue period, when threat estimates are generated, and post-cue period, when –PEs are generated and will directly determine the impact of ELS, and neuron-type deletion, on single-unit activity. In Aim 2, we will use optogenetic inhibition during the cue period, when threat estimates are generated, and the post-cue period, when –PEs are generated, to demonstrate causal roles for, DR GABA, DR 5HT, DR Non-5HT populations, and DR-to-BLA projections in fear to uncertainty. This will uncover causal roles for DR neuron-types, and direct DR to BLA projections, in accurate threat estimation in normal and ELS individuals. In Aim 3, we will combine neuron-type-specific optogenetic excitation of the DR with single-unit recording in the BLA of ELS rats. DR GABA neurons will be stimulated during cue periods, and DR Non-5HT neurons will be stimulated during –PE periods, in order to restore appropriate fear, and BLA neural activity, to uncertainty. This proposal will demonstrate that ELS reprograms neuron-type-specific signaling in the DR-to- BLA circuit to inflate threat estimation. The results will uncover novel targets for pharmacotherapies to restore accurate estimation in ELS individuals. The long term goal of this research is to map a complete neural for accurate threat estimation, reveal how ELS disrupts circuit function, and use this knowledge to design fully effective therapies to restore accurate threat estimation in ELS-affected individuals.