DESCRIPTION (provided by applicant): Principal neurons of the medial superior olive (MSO) compute sound location from interaural time disparities (ITDs) introduced by the physical separation of the ears. In turn, they encode horizontal sound location in their rate of action potential (AP) firing. It is not fully understood how MSO neurons' intrinsic electrical properties combine with their highly structured morphology (ie., channel expression/distribution) to support this submillisecond computation, particularly in the face of high frequency firing found in auditory brainstem pathways. Recent work shows AP backpropagation into the soma and dendrites is downregulated developmentally such that somatic APs are small in electrically mature neurons. Experiments in this grant will explore the mechanisms and functional significance for the electrical segregation of AP signaling from synaptic integration using immunohistochemistry and slice electrophysiology techniques. Results will uncover how the membrane properties of MSO neurons help to surmount the unique computational challenges associated with encoding brief sound localization cues embedded in high frequency signals.