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 bisynaptic 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.