Synaptic Plasticity within Neural Circuits Critical for Fear Memory Retrieval

项目摘要/摘要 记忆的形成、存储和提取是健康幸福的关键组成部分，而在这些方面存在功能障碍 这一过程可能导致毁灭性的健康问题。这个项目的长期目标，与 这项提议的培训目标，是增进我们对蛋白质之间关系的理解 泛素-蛋白酶体系统的降解与记忆和突触可塑性的稳定性 在特定的大脑回路中。UPS是一条主要的监管途径，负责识别和 清除异常或受损的蛋白质，而记忆不稳定(即重新巩固)指的是 通过记忆检索使先前合并的记忆变得不稳定的过程。在这份提案中， 我们将确定精选神经回路中的活动如何影响蛋白质降解和记忆 不稳定过程，通过定量α-氨基-3-羟基-5-甲基-4- 异恶唑丙酸(AMPA)受体亚单位，在恐惧条件反射(FC)记忆提取后。一 前额叶(PL)皮质-杏仁外侧核(LA)回路是FC记忆提取的重要神经回路。在……里面 目标1(实验1)，我们将确定在恐惧过程中是否选择性地抑制PL-to-LA神经元投射 记忆恢复足以影响行为、UPS活性、AMPA受体亚单位表达和其他 LA突触的AMPA受体相关蛋白。目标2的目标是确定 中脑导水管周围灰质腹外侧区较大的vlPAG-PL-LA环路，尤其是在LA水平 突触。在实验中2，我们将测试静音vlPAG-to-PL投影是否足以影响行为，UPS 活性，AMPA受体的表达，以及其他蛋白在LA突触的表达。最后，在Exp.3、我们 将测试静音PL-to-VlPAG预测是否足以影响这些相同的措施。在所有实验中 我们还将对从LA、PL和vlPAG收集的组织进行荧光原位杂交，以 描述这些投射中涉及的细胞类型。在所有三个实验中，我们都将使用双重病毒Cre- 依赖抑制光遗传学方法和在FC记忆过程中用激光沉默这些投射 取回后，将收集大脑进行脑组织生化分析。这种方法将使我们能够 确定沉默这些投射是否足以影响行为表现、蛋白分解活性和 记忆不稳定的过程。这项工作是创新的，因为几乎没有做过什么来表征 蛋白质降解与选择神经回路中记忆失稳之间的关系 情绪记忆功能。此外，还没有做什么工作来确定vlPAG的功能作用。 在提取恐惧记忆的过程中反馈到大脑皮层区域。最后，这项工作意义重大，因为这些 这些发现将促进对蛋白质动态平衡、记忆失稳和神经回路的理解， 这将为治疗与记忆衰弱相关的心理健康障碍提供新的方向。

Project Summary / Abstract Memory formation, storage, and retrieval are critical components of healthy well-being, and dysfunction in these processes can lead to devastating health problems. The long-term goals of this project, which are in parallel with the training goals of this proposal, is to advance our understanding of the relationship between protein degradation through the ubiquitin-proteasome system (UPS) and the stability of memory and synaptic plasticity within specific brain circuits. The UPS is a major regulatory pathway that is responsible for the recognition and clearance of abnormal or damaged proteins, while memory destabilization (i.e. reconsolidation) refers to the process by which a previously consolidated memory can be destabilized by memory retrieval. In this proposal, we will identify how activity within select neural circuits affects both protein degradation and memory destabilization processes, as measured through quantification of α-amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid (AMPA) receptor subunits, following fear conditioning (FC) memory retrieval. One neural circuit important for FC memory retrieval is the prelimbic (PL) cortex-lateral amygdala (LA) circuit. In Aim 1 (Experiment 1), we will determine if selective inhibition of PL-to-LA neuronal projections during fear memory retrieval is sufficient to affect behavior, UPS activity, AMPA receptor subunit expression, and other AMPA receptor-associated proteins at LA synapses. The goal of Aim 2 is to determine the functional role of the ventrolateral periaqueductal gray (vlPAG) in a larger vlPAG-PL-LA circuit, particularly at the level of LA synapses. In Exp. 2, we will test whether silencing vlPAG-to-PL projections is sufficient to affect behavior, UPS activity, AMPA receptor expression, and the expression of other proteins at LA synapses. Finally, in Exp. 3, we will test whether silencing PL-to-vlPAG projections is sufficient to affect these same measures. In all experiments we will also perform fluorescent in situ hybridization on tissue collected from the LA, PL, and vlPAG to characterize the cell types involved in these projections. In all three experiments we will use a dual-virus, Cre- dependent inhibitory optogenetic approach and silence these projections with a laser during FC memory retrieval, and brains will be collected for biochemical analysis of brain tissue. This approach will allow us to determine if silencing these projections is sufficient to affect behavioral performance, proteolytic activity, and memory destabilization processes. This work is innovative because little has been done to characterize the relationship between protein degradation and memory destabilization within select neural circuits essential for emotional memory functioning. Furthermore, little work has been done to determine the functional role of vlPAG feedback to cortical regions during the retrieval of a fear memory. Finally, this work is significant because these findings will advance the understanding of protein homeostasis, memory destabilization, and neural circuits, which will provide new directions for the treatment of debilitating memory-related mental health disorders.