During fear learning, associations between a sensory cue (conditioned stimulus, CS) and an aversive stimulus (unconditioned stimulus, US) are formed in specific brain circuits. The lateral amygdala (LA) is involved in CS-US integration
however, US pathways to the LA remain understudied. Here, we investigated whether the posterior insular cortex (pInsCx), a hub for aversive state signaling, transmits US information to the LA during fear learning. We find that the pInsCx makes a robust, glutamatergic projection specifically targeting the anterior LA. In vivo Ca