Circuitry and Function of the Dorsal Cochlear Nucleus

Abstract

In Chapter 2 of this volume, Smith and Spirou describe the wonderful complexity of the brainstem auditory system. This system forms a collection of parallel pathways that diverge at the first auditory synapse in the brainstem, in the cochlear nucleus (CN), and then converge again, at least in a gross anatomical sense, in the inferior colliculus (for abbreviations, see Table 5.1). The CN is a well-studied collection of neural circuits that are diverse both in anatomical and physiological terms (reviewed by Cant 1992; Rhode and Greenberg 1992; Young 1998). These vary from the simplest system, the bushy cells of the ventral cochlear nucleus (VCN; see Yin, Chapter 4), to the most complex, in the dorsal cochlear nucleus (DCN). The DCN differs from other parts of the CN by having an extensive internal neuropil formed by groups of interneurons (Lorente de Nô 1981; Osen et al. 1990). As a result, the DCN makes significant changes in the auditory representation from its inputs to its outputs. In this chapter, the neural organization of the DCN is reviewed, paying most attention to data from the cat. The response properties of DCN neurons are discussed in the context of its neural organization and related to data on the functional role of the DCN in hearing.