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Parallel auditory pathways: Projection patterns of the different neuronal populations in the dorsal and ventral cochlear nuclei

Department of Neurobiology, Duke University Medical Center, P.O. Box 3209, Durham, NC 27710, USA.
Brain Research Bulletin (Impact Factor: 2.97). 07/2003; 60(5-6):457-74. DOI: 10.1016/S0361-9230(03)00050-9
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ABSTRACT The cochlear nuclear complex gives rise to widespread projections to nuclei throughout the brainstem. The projections arise from separate, well-defined populations of cells. None of the cell populations in the cochlear nucleus projects to all brainstem targets, and none of the targets receives inputs from all cell types. The projections of nine distinguishable cell types in the cochlear nucleus-seven in the ventral cochlear nucleus and two in the dorsal cochlear nucleus-are described in this review. Globular bushy cells and two types of spherical bushy cells project to nuclei in the superior olivary complex that play roles in sound localization based on binaural cues. Octopus cells convey precisely timed information to nuclei in the superior olivary complex and lateral lemniscus that, in turn, send inhibitory input to the inferior colliculus. Cochlear root neurons send widespread projections to areas of the reticular formation involved in startle reflexes and autonomic functions. Type I multipolar cells may encode complex features of natural stimuli and send excitatory projections directly to the inferior colliculus. Type II multipolar cells send inhibitory projections to the contralateral cochlear nuclei. Fusiform cells in the dorsal cochlear nucleus appear to be important for the localization of sounds based on spectral cues and send direct excitatory projections to the inferior colliculus. Giant cells in the dorsal cochlear nucleus also project directly to the inferior colliculus; some of them may convey inhibitory inputs to the contralateral cochlear nucleus as well.

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    • "The CNC distributes the incoming auditory information to distinct ascending pathways in the brainstem (Fig. 3). Major projections of the DCN innervate the contralateral nuclei of the LL and the IC (Cant and Benson 2003). The VCN projects mainly into the region of the ipsilateral and contralateral SOC. "
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    • "The third layer, the deep or polymorphic layer, has an assortment of cell types. Deep to the DCN are the fibers of the dorsal acoustic stria (das), comprised of the axons of the DCN projection neurons as well as other fibers from multiple brain regions projecting to the DCN (Barnes et al., 1943; Gacek, 1973; Adams and Warr, 1976; Masterton and Granger, 1988; Cant and Benson, 2003; Smith et al., 2005). "
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    • "This result verifies the tonotopic-specific distribution through the cell body and dendrites of CRNs and suggests that both CRNs and DCN neurons receive similar acoustic information. DCN projects to the IC (Beyerl, 1978; Oliver and Shneiderman, 1991; Oliver et al., 1999; Cant and Benson, 2003), which is known to participate in the modulation of the ASR (Leitner and Cohen, 1985; Fendt et al., 2001; Yeomans et al., 2006; Gómez-Nieto et al., 2008a, 2013). It is, therefore, likely that DCN might provide acoustic information to ASR modulation pathways rather than being necessary for the initiation and elicitation of the ASR. "
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