Dissection of cortico-amygdala circuits controlling aversive behavior using novel mono- and bi-synaptic retrograde viral tools

长期以来，杏仁核一直被认为是协调习得性和先天恐惧反应的中心区域。虽然迄今为止的大多数研究都集中在杏仁核本身，以及它在解剖学和功能上不同的核之间的相互作用上，但越来越清楚的是，杏仁核嵌入在全脑回路中，从中整合信息来调节厌恶行为的表达。特别是，杏仁核接收到强烈的皮层输入，这些输入是根据不同物种和感觉模式的共同原则组织的：信息在皮层级联流动，从初级感觉皮层通过次级皮层区域流向高阶关联皮层，沿着这条通路观察到与杏仁核的连接强度增加。然而，我们对这些回路在已识别的、突触连接的神经元（而不仅仅是区域间追踪）水平上的组织知之甚少，他们在厌恶行为时向杏仁核提供的信息，以及行为的哪些方面需要这些信号。在这里，我们的目标是开发新的单突触和双突触病毒追踪工具，我们将其与现有的转基因和病毒方法结合使用，以靶向功能成像和光遗传学操作嵌入特定皮质网络中的神经元，这些网络与小鼠中已识别的杏仁核神经元单突触和双突触连接。这将与解决习得性和先天恐惧的范例相结合，以确定这些回路如何促进行为，使用信息流从初级到次级听觉皮层，再到杏仁核，以及从高阶关联皮层（岛叶皮层）到杏仁核的交流作为模型。除了这些特定的目标，我们期望新型病毒工具的开发和验证也将使未来在其他大脑区域的特定大规模网络的解剖成为可能。

The amygdala has long been established as a central area orchestrating learned and innate fear responses. While most research to date has focused on the amygdala itself, and interactions between its different anatomically and functionally distinct nuclei, it is becoming increasingly clear that the amygdala is embedded in brain-wide circuits from which it integrates information to regulate expression of aversive behaviors. In particular, the amygdala receives strong cortical input that is organized according to a common principle across different species and sensory modalities: information flows in cortical cascades from primary sensory cortex via secondary cortical areas towards higher order association cortex, with increasing connection strength to the amygdala observed along this pathway. However, we know very little about the organization of these circuits at the level of identified, synaptically connected neurons (rather than mere inter-area tracing), the information they supply to the amygdala during aversive behaviors, and for which aspects of behavior these signals are required. Here, our goal is to develop novel mono- and bi-synaptic viral tracing tools that we use in combination with existing transgenic and viral approaches to target functional imaging and optogenetic manipulations to neurons embedded within specific cortical networks that are mono- and bi-synaptically connected to identified amygdala neurons in the mouse. This will be combined with paradigms addressing learned and innate fear to determine how these circuits contribute to behavior, using information flow from primary to secondary auditory cortex and further to the amygdala and communication from a higher order association cortex (insular cortex) to the amygdala as models. In addition to these specific aims, we expect that the development and validation of the novel viral tools will also enable future dissection of specific large-scale networks in other brain areas.