Many animals communicate with members of their own species using specific sounds. These sounds are behaviorally relevant to the animals because they facilitate important behaviors such as maintaining a territory or finding offspring on return from foraging. When an animal hears one of these behaviorally relevant sounds, it must make an appropriate response based on the information in the sound. To do this, the auditory system must detect, discriminate and categorize each of the sounds. The goal of the current project is to understand the strategies and mechanisms that the auditory system utilizes to achieve these tasks. Electrophysiological techniques will be used to determine how individual neurons in the auditory midbrain of mice encode behaviorally relevant sounds. Sounds emitted by mice during different behaviors (such as establishing dominance and aggressive interactions) will be used as stimuli to evoke responses from individual neurons. Differences in the rate and timing of individual neural responses to different sounds will be used to determine the strategies that the auditory midbrain uses to encode behaviorally relevant sounds. The importance of this research is in understanding how the brain has evolved to optimally encode behaviorally relevant sounds. This research will increase the understanding of how sound perception helps animals survive. A variety of training opportunities will be provided during this project. Post-doctoral, graduate, undergraduate and high school students will be trained in neurophysiological techniques. Students will also gain training in quantitative techniques through active collaborations with mathematicians. This project will engage minority students in science through research opportunities, and research and teaching activities will be integrated in undergraduate classes. Presentations will be given to schools and community groups to illustrate the importance of science.