The purpose of the project is to study the biochemistry, morphology, pharmacology and physiology of synaptic transmission and neuronal connection of nerve cells of the mammalian cochlear nucleus: 1. Complementing previously published findings on the cytochemically localized aspartate aminotransferase-like immunoreactivity we have now found highly concentrated such activity in photoreceptors of the guinea pig. 2. Synapses between the auditory nerve and cells in the cochlear nucleus are being studied in vitro, using microiontophoretic techniques applied to a brain slice preparation.