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: 2.72).
07/2003; 60(5-6):457-74. DOI: 10.1016/S0361-9230(03)00050-9
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.
Available from: Tina Schlüter
- "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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ABSTRACT: A defining feature of the mammalian auditory system is the extensive processing of sound information in numerous ultrafast and temporally precise circuits in the hindbrain. By exploiting the experimental advantages of mouse genetics, recent years have witnessed an impressive advance in our understanding of developmental mechanisms involved in the formation and refinement of these circuits. Here, we will summarize the progress made in four major fields: the dissection of the rhombomeric origins of auditory hindbrain nuclei; the molecular repertoire involved in circuit formation such as Hox transcription factors and the Eph-ephrin signaling system; the timeline of functional circuit assembly; and the critical role of spontaneous activity for circuit refinement. In total, this information provides a solid framework for further exploration of the factors shaping auditory hindbrain circuits and their specializations. A comprehensive understanding of the developmental pathways and instructive factors will also offer important clues to the causes and consequences of hearing-loss related disorders, which represent the most common sensory impairment in humans.
Cell and Tissue Research 01/2015; 361(1). DOI:10.1007/s00441-014-2110-7 · 3.57 Impact Factor
Available from: sciencedirect.com
- "The IC is also the initial converging center of the central auditory system (Casseday et al., 2002; Ehret, 1997). Once the sound information is transmitted from the auditory nerve to the brain, it gets processed across multiple structures within the brainstem through several diverging pathways (Cant and Benson, 2003). The ascending sound information and pathways then converge, for the most part, into the ICC en route to the thalamus and cortex. "
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ABSTRACT: The cochlear implant is considered one of the most successful neural prostheses to date, which was made possible by visionaries who continued to develop the cochlear implant through multiple technological and clinical challenges. However, patients without a functional auditory nerve or implantable cochlea cannot benefit from a cochlear implant. The focus of the paper is to review the development and translation of a new type of central auditory prosthesis for this group of patients, which is known as the auditory midbrain implant (AMI) and is designed for electrical stimulation within the inferior colliculus. The rationale and results for the first AMI clinical study using a multi-site single-shank array will be presented initially. Although the AMI has achieved encouraging results in terms of safety and improvements in lip-reading capabilities and environmental awareness, it has not yet provided sufficient speech perception. Animal and human data will then be presented to show that a two-shank AMI array can potentially improve hearing performance by targeting specific neurons of the inferior colliculus. Modifications to the AMI array design, stimulation strategy, and surgical approach have been made that are expected to improve hearing performance in the patients implanted with a two-shank array in an upcoming clinical trial funded by the National Institutes of Health. Positive outcomes from this clinical trial will motivate new efforts and developments toward improving central auditory prostheses for those who cannot sufficiently benefit from cochlear implants.
Copyright © 2015. Published by Elsevier B.V.
Hearing Research 01/2015; 322. DOI:10.1016/j.heares.2015.01.006 · 2.97 Impact Factor
Available from: Senthilvelan Manohar
- "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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ABSTRACT: The dorsal cochlear nucleus (DCN) is a brainstem structure that receives input from the auditory nerve. Many studies in a diversity of species have shown that the DCN has a laminar organization and identifiable neuron types with predictable synaptic relations to each other. In contrast, studies on the human DCN have found a less distinct laminar organization and fewer cell types, although there has been disagreement among studies in how to characterize laminar organization and which of the cell types identified in other animals are also present in humans. We have reexamined DCN organization in the human using immunohistochemistry to analyze the expression of several proteins that have been useful in delineating the neurochemical organization of other brainstem structures in humans: nonphosphorylated neurofilament protein (NPNFP), nitric oxide synthase (nNOS), and three calcium-binding proteins. The results for humans suggest a laminar organization with only two layers, and the presence of large projection neurons that are enriched in NPNFP. We did not observe evidence in humans of the inhibitory interneurons that have been described in the cat and rodent DCN. To compare humans and other animals directly we used immunohistochemistry to examine the DCN in the macaque monkey, the cat, and three rodents. We found similarities between macaque monkey and human in the expression of NPNFP and nNOS, and unexpected differences among species in the patterns of expression of the calcium-binding proteins. Anat Rec, 2014. © 2014 Wiley Periodicals, Inc.
The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 10/2014; 297(10). DOI:10.1002/ar.23000 · 1.54 Impact Factor
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