Developmental Changes and Cellular Plasticity in the Superior Olivary Complex

Abstract

The superior olivary complex (SOC) is a conspicuous structure in the mammalian central auditory system. It is located ventrally in the pontine brain stem underneath the cerebellum and consists of several third-order nuclei. The general organization of the SOC is illustrated in Figure 3.1A. Usually three principal SOC nuclei are identified (for abbreviations, see list at end of chapter), the lateral superior olive (LSO), the medial superior olive (MSO), and the medial nucleus of the trapezoid body (MNTB; Irving and Harrison 1967; for review see Schwartz 1992; see also Reuss 2000). These principal nuclei are surrounded by periolivary regions: the superior paraolivary nucleus (SPN), the lateral nucleus of the trapezoid body (LNTB), and the ventral nucleus of the trapezoid body (VNTB). In the rodent brain, the nomenclature occasionally refers to the LNTB and VNTB as the lateroventral (LVPO) and medioventral periolivary region (MVPO), respectively (Osen et al. 1984; Thompson and Thompson 1991). In cats and bats, a dorsomedial periolivary nucleus (DMPO) has been described and appears to be equivalent to the SPN of the rodent brain (Schofield and Cant 1991; Schwartz 1992; Ostapoff et al. 1997; Grothe and Park 2000). Rostrally and caudally to the SOC proper, two additional areas are located that are generally called the rostral and the caudal periolivary region (RPO and CPO, respectively).