PROJECT SUMMARY/ABSTRACT Effective interpretation of sound requires discriminating acoustic features and linking them to appropriate behavioral responses depending on past experience. Much remains unknown, however, about the roles that different neural pathways play in representing, learning, and performing these associations. As a step toward addressing the long-term goal of understanding how the nervous system flexibly links sounds to actions, this research will study the contributions of the multiple auditory pathways that target the striatum, the main input stage of the basal ganglia and a key structure in the regulation of motor behavior. Specifically, the project will focus on the flow of information from the auditory thalamus as well as primary and non-primary areas of the auditory cortex to the posterior tail of the striatum. The central hypothesis is that the various auditory cortical and thalamic pathways to the striatum all play distinct roles during learning and execution of sound-driven decisions. This work will consist of developing theoretical models of sound representation and learning in the multiple auditory pathways converging on the striatum, as well as carrying out experiments in mice trained to perform acoustic discrimination tasks in order to test and refine these models. These experiments will take advantage of novel techniques for reversible manipulation of specific neural pathways while monitoring large numbers of neurons simultaneously during behavior. The project is organized in three aims. The first aim is to determine the conditions in which auditory cortico-striatal and thalamo-striatal pathways play distinct roles during performance of sound-action association tasks. The second aim is to determine the roles of auditory cortical vs. thalamic pathways to the striatum during learning of these tasks. The third aim is to identify the acoustic features of natural sounds conveyed by distinct auditory cortical fields to the striatum. Together, these studies will reveal the relative contributions of distinct neural pathways to sound-driven behavior in the healthy brain, and they will provide insights into how auditory cognition can be affected by disease.