In Vivo Synaptic Transmission in Mouse Models for Neurological Disorders

Abstract

Before you can hear a sound, it has to pass the outer and the middle ear and reach the cochlea. The cochlea acts as a frequency analyzer: it separates sounds into different frequency bands. This information is relayed by the auditory nerve, and is further processed in the brainstem nuclei. To determine the location of a source in the horizontal plane, the binaural processing of auditory signals perceived by two ears is crucial. Two different cues are used to accomplish this: differences in sound intensity between both ears (interaural level differences, ILDs) and differences in arrival times between both ears (interaural time differences, ITDs). Sounds are louder at the ear that is closest to the sound source, and they arrive earlier at the ear that is closest. The initial processing of ILDs and ITDs takes place in the superior olivary complex (SOC), a collection of about nine auditory nuclei in the ventral brainstem.