SEROTONIN AND SEROTONIN RECEPTORS IN THE CENTRAL AUDITORY-SYSTEM

Immunohistochemical and ligand-binding techniques were used to visuali ze the neurotransmitter serotonin and one of its receptors, the 5-HT1A subtype, in auditory nuclei of the brainstem. Serotonergic fibers and terminal endings were found in all auditory nuclei extending from the cochlear nucleus to the inferior calliculus, including the superior o livary complex and the nuclei of the lateral lemniscus. The density of the innervation varied between and within each nucleus. All serotoner gic cell bodies were located outside the auditory nuclei. The 5-HT1A r eceptor subtype was found in the cochlear nucleus as well as in the in ferior colliculus. With no serotonergic cell bodies present in the aud itory nuclei, the present neuroanatomic and neurochemical findings sup port behavioral and neurophysiologic findings that the serotonergic sy stem may modulate central auditory processing.