Acetylcholine as a Transmitter in the Cat Auditory System1

The ACh content of the cat cochlear nucleus was determined following intraventricular injection of hemicholinium. The data presented shows that the level of ACh can be greatly reduced by stimulation of a centrifugal pathway arising from the ipsilateral superior olive. Additional data is provided by a single neurone study which shows that this stimulation also blocks the normal physiological effects of the pathway. This evidence supports the hypothesis that ACh is a transmitter in a centrifugal pathway within the cat auditory system.