Fear conditioning is a widely used paradigm to study learning and memory formation. The amygdala is a central part of the neural circuit that mediates auditory fear learning in which tones are paired with timed footshocks. Tone information reaches the amygdala via a fast route via the thalamus and a slower route via the auditory cortex. Footshock information reaches the amygdala via the posterior thalamus. In this grant we aim to understand how sound and footshock information reaches the amygdala, the cells that are innervated by these two inputs and how neural activity in the basolateral amygdala encodes sound. We will use single unit recordings in vivo to study how sound is encoded in the basolateral amygdala. Cross-correlation analysis will be used to decipher the networks of neurons that are engaged during fear learning. To understand how auditory information reaches the amygdala we will use paired whole-cell recordings in acute brain slices, in combination with optogenetic stimulation to understand the physiology of cortical and thalamic auditory input as well somatosensory input to the amygdala. Three strains of transgenic mice will be used to distinguish inputs to pyramidal neurons from those to different types of interneurons. These studies will enable a complete understanding of the neural circuits in the basolateral amygdala that process sound and footshock information and how animals learn to associate some sounds with an aversive outcome. In the long term these data may help in the design of novel therapies to treat anxiety disorders.