In vitro studies of neuromodulation and plasticity in the dorsal cochlear nucleus

The dorsal cochlear nucleus (DCN), a division of the cochlear nuclear complex, has been the subject of intense interest for its role in auditory processing and hearing disorders. The tonotopic layout of DCN principal cells and the refinement of processing of auditory signals by interneurons are together thought to permit encoding of sound source elevation. However, the many cell types and complex connectivity of the DCN suggest more diverse functions than localization. A prominent non-auditory input to the DCN has been proposed to assist in such functions as orienting to sounds of interest, detecting moving sounds, or cancelling self-generated sounds. Synaptic plasticity in the DCN may be essential for dynamic tuning of non-auditory input. Indeed, long-term changes in synaptic or membrane properties could underlie tinnitus, which is associated with hyperactivity in the DCN in some animal models. Finally, the DCN is invested with wide-ranging neuromodulatory mechanisms, suggesting that changes in the behavioral state of animals associated with such neuromodulatory systems might alter sensory processing at the earliest stages of the auditory pathway. This review will focus on studies that have utilized the in vitro brain slice approach to identify basic mechanisms of synaptic plasticity and neuromodulation in the DCN.