The neuronal architecture of the cochlear nucleus of the cat

Abstract

A detailed parcellation of the entire cochlear nucleus of the cat was prepared with the Nissl and Protargol methods in the form of a cytoarchitectonic atlas. Neuronal cell types were characterized in rapid Golgi impregnations. Golgi impregnations were used to define the specific features of the mature neuronal types. Neurons from the Golgi preparations were systematically mapped according to type and location in serial sections. These neurons were then plotted in corresponding positions in the cytoarchitectonic atlas. This combined GolgiNissl approach provides a scheme in which neuronal types, defined in terms of a number of functionally significant features, can be precisely localized within the cochlear nucleus.The cochlear nucleus provides the first opportunities for recoding of signals from the auditory nerve. So the neuronal architecture of the cochlear nucleus must play a key role in defining the functional organization of the ascending auditory system. The structural organization of the cochlear nucleus is complicated by the fact that it is not a single nucleus but a complex of distinct neuronal populations. Previous investigators, using several histological techniques, have attempted to identify and describe types of neurons and to subdivide the nucleus. Most schemes of parcellation have been based on cell body stains, especially the Nissl method, whereas neuronal cell types have been characterized with a variety of techniques, including Nissl, reduced silver, and Golgi methods (e.g., in the cut: Ram6n y Cajal,

Connections between the cochlear nuclei in guinea pig

“…Since we were unable to consistently visualize dendrites or intracellular features, we could not assign cells to the categories described by other investigators (Osen, 1969;Brawer et al, 1974;Cant and Morest, 1984;Moore, 1986;Hackney et ai., 1990). Instead, we measured soma size (using the long axis measurement) and described soma shape.…”

Onset Neurones in the Anteroventral Cochlear Nucleus Project to the Dorsal Cochlear Nucleus

“…Some have very distinctive morphologies, such as the granular, Golgi, and octopus cells and the globular and spherical bushy cells. However, others form part of a diverse class of stellate or multipolar cells which vary in size, from small to giant, with either smooth dendrites or varying densities of spines (Osen 1969;Brawer et al 1974). Bushy cells provide more-or-less faithful transmission of auditory nerve firing patterns (Pfeiffer 1966) and project this information into pathways for comparison of the activity from the two ears to extract cues for localizing sounds.…”

Postsynaptic Targets of Type II Auditory Nerve Fibers in the Cochlear Nucleus.

“…Type I fibers have an excitatory influence on their postsynaptic targets, leading to discharge of cochlear-nucleus neurons (Pfeiffer 1966;Golding et al 1995;Kopp-Scheinpflug et al 2002). Type I targets in the cochlear nucleus are a variety of types of neurons (Brawer and Morest 1975;Rouiller et al 1986), which have been classified by their morphology using different stains (Osen 1969;Brawer et al 1974). The postsynaptic targets of type II fibers in the cochlear nucleus are almost entirely unknown.…”