Thalamocortical Auditory System

Abstract

Since the Golgi study of cats by Morest (1964), subdivision of the medial geniculate body (MG) into three major divisions is generally accepted for most species, although ideally this should be based on examination in Golgi material of dendritic arrangements. Morest and Winer (1986) stress the similarity between cats and opossums in the preservation of the major divisions of the MG when studied with Golgi material, although they indicate that boundaries between subdivisions in Nissl-stained material are less conspicuous in opossums than in cats. One difference they noted was the paucity of Golgi type II cells (short axon cells which act as local interneurons) in opossums. The MG of brushtail possums (Aitkin and Gates 1983) and Northern quolls (Kudo et al. 1989) has also been subdivided into ventral, medial, and dorsal divisions on the basis of packing density and dendritic labeling with horseradish peroxidase.