The goal of this research is to understand the cellular mechanisms of acoustic information processing in the cochlear nucleus of the barn owl. Both physiological and anatomical methods will be used. Extracellular single unit recordings will explore the relationships between the response properties of auditory nerve inputs and magnocellular and angular cochlear nucleus outputs. These experiments will test whether the segregation of phase and intensity processing that we have observed in the cochlear nuclei originates in the cochlear nuclei or is already present in auditory nerve. Phase sensitivity will be assessed by recording spike timing relative to stimulus phase. Sensitivity to intensity will be evaluated by examining temporal patterns of neural response over a range of intensities at both the auditory nerve and cochlear nucleus levels. By enabling a comparison of the input to a cochlear nucleus with its output, these experiments will help us to determine how information is processed within each of the cochlear nuclei. Golgi methods will provide a description of the cell types found in each nucleus. Due to the physical separation of the two cochlear nuclei in birds and to the relative homogeneity of response properties within each nucleus, descriptions of cellular morphology may provide some insights into morphological - physiological correlations. In future work, I will test these correlations using intracellular recording and dye injection methods supplemented with computer simulations of neural transmission.
