The goal of the research is a detailed description of the synaptic organization of parts of the auditory system in terms of the specific neuronal types that it comprises. The objective is to gain an understanding of the principles of synaptic organization and of the cytological and connectional features that form the morphological basis for stimulus coding by sensory neurons. The Golgi methods and cell and fiber stains will be used to reveal normal morphology in the light microscope. Silver degeneration techniques and methods relying on axonal transport of radioactive amino acids or horseradish peroxidase will be used to trace connections of the neurons in the cochlear nucleus. The results of the investigations with the light microscope will be correlated with electron microscopical observations of normal and experimentally altered material. Correlations of the results of the light and electron microscopic findings will allow the description of parts of the auditory system in terms of the connections formed among specific types of neurons. The areas of study will be localized carefully since the studies are designed to allow correlations with results of electrophysiological and biochemical studies of the same neurons. Thus, results from several disciplines may be brought to bear on the problem of the mechanisms of signal transformations in the auditory system.