The auditory system is highly specialized to encode frequency and temporal elements of sound, a process critical for survival and for understanding behaviorally relevant communication signals. Fundamental to such specializations is the structure and function of individual neurons. This is especially true in the cochlear nucleus (CN). Here, individual neurons have unique anatomical and physiological properties that enable them to accurately encode frequency and temporal elements of sound for tasks related to sound localization and signal extraction in noise. These anatomical and physiological properties include the large endbulb of Held synapse onto the soma of CN neurons, and the considerable expression of voltage dependent potassium channels. Interestingly, this uniqueness is not shared across different frequency regions within the CN. This raises an important question. What anatomical and physiological differences are needed to encode varying frequency and temporal elements of sound in the CN? Much is known about the specialized neurons of the avian cochlear nucleus magnocellularis (NM, analogous to the mammalian anteroventral CN, AVCN) in both its structure and function in processing mid- to high frequency sounds. Much less is known about the structure and function of neurons that are responsible for encoding low frequency sound < 500 Hz. Our preliminary data suggest specialized neuronal cell types, neuronal connectivity and unique biophysical properties for low frequency processing in the low frequency NM that is distinct from mid- or high frequency NM regions. However, underlying mechanisms for these specializations and their contribution to low frequency auditory processing are largely unexplored. This proposal will address this by investigating anatomical specializations and physiological mechanisms that are unique to the processing of low frequency sound.
