Article

Connections between the cochlear nuclei in guinea pig

Department of Otolaryngology, Medical College of Ohio, Toledo, Ohio, USA; Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Michigan, USA
Hearing Research (Impact Factor: 2.54). 10/1992; DOI: 10.1016/0378-5955(92)90199-W
Source: PubMed

ABSTRACT This study provides a detailed analysis of the appearances and distributions of neurons projecting from one cochlear nucleus to the other. Injections of wheatgerm agglutinin conjugated to horseradish peroxidase were made into ventral or dorsal cochlear nucleus of the guinea pig. Retrogradely labeled cells in the opposite cochlear nucleus were examined and quantified. Three major categories of labeled cells were discerned on the basis of their soma shape: elongate, round-to-oval, and polygonal. All injections resulted in widespread labeling of cells in all of these categories, but especially round-to-oval cells, in the opposite ventral cochlear nucleus and sparse labeling in the dorsal cochlear nucleus. The results suggest that there is a significant cochlear nucleus commissural projection involving heterogeneous cell types which could have diverse functions in binaural auditory signal processing.

0 Bookmarks
 · 
84 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The number of calbindin D-28k and parvalbumin immunoreactive (IR) neurons were characterized on sections from the cochlear nucleus, dorsal cochlear nucleus (DCN) and posteroventral cochlear nucleus (PVCN) using two-dimensional quantification. After noise exposure (6–12 kHz, 2 h, at either 80 dB SPL or 103 dB SPL), the number of calbindin and parvalbumin immunoreactive neurons increased in CBA/CBA mice. Quantitative analysis of calbindin-IR in the PVCN did not show a statistically significant difference between any of the groups, whereas statistically significant differences in calbindin-IR were found in the DCN for the 103 dB and 80 dB group compared to the control group, and 103 dB compared to the 80 dB group, respectively. A statistically significant increase in the number of parvalbumin-IR neurons in the PVCN and the DCN was evident in the 103 dB and 80 dB group compared to the control group, and in the 103 dB compared to the 80 dB group. The data indicate that increasing sound stimulation causes a graded increase in the expression of calcium-binding protein immunoreactivity in the DCN and PVCN neurons and neuropil. This increase of protein expression is due to increased positive immunoreactivity in `silent' neurons. These findings implicate that these neurons have the possibility to react against trauma and display calbindin or parvalbumin as a rescue event. The ability to map sound-induced calcium-binding protein changes in auditory neurons may be useful in future studies designed for detecting early patterns of neurodegeneration and neuroprotection in the central auditory pathway.
    Brain Research - BRAIN RES. 01/1998; 800(1):86-96.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Direct projections from the cochlear nucleus (CN) to the medial geniculate body (MG) mediate a high-speed transfer of acoustic information to the auditory thalamus. Anderson etal. (2006) used anterograde tracers to label the projection from the dorsal CN (DCN) to the MG in guinea pigs. We examined this pathway with retrograde tracers. The results confirm a pathway from the DCN, originating primarily from the deep layers. Labeled cells included a few giant cells and a larger number of small cells of unknown type. Many more labeled cells were present in the ventral CN (VCN). These cells, identifiable as multipolar (stellate) or small cells, were found throughout much of the VCN. Most of the labeled cells were located contralateral to the injection site. The CN to MG pathway bypasses the inferior colliculus (IC), where most ascending auditory information is processed. Anderson etal. (2006) hypothesized that CN-MG axons are collaterals of axons that reach the IC. We tested this hypothesis by injecting different fluorescent tracers into the MG and IC and examining the CN for double-labeled cells. After injections on the same side of the brain, double-labeled cells were found in the contralateral VCN and DCN. Most double-labeled cells were in the VCN, where they accounted for up to 37% of the cells labeled by the MG injection. We conclude that projections from the CN to the MG originate from the VCN and, less so, from the DCN. A significant proportion of the cells send a collateral projection to the IC. Presumably, the collateral projections send the same information to both the MG and the IC. The results suggest that T-stellate cells of the VCN are a major source of direct projections to the auditory thalamus.
    Frontiers in Neuroanatomy 01/2014; 8:10. · 4.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Die Ursache von Tinnitus, Schwindel und Hörstörungen kann in pathologischen Prozessen an der Halswirbelsäule (HWS) und im Kiefergelenk liegen. Bei Nachweis dieser Ursachen handelt es sich um einen somatosensorischen Tinnitus (SST). Für Afferenzen aus der HWS konnten entsprechende Projektionen der neuronalen Verschaltungen in den Nucleus cochlearis nachgewiesen werden. Es ist von einem reflexartigen Einfluss der HWS auf diesen Hörkern auszugehen. Das Tinnitus-Therapiekonzept der Berliner Charité beinhaltet eine tagesklinische Zusammenarbeit von HNO-Ärzten und vielen anderen Disziplinen. Es wurde ein standardisierter Untersuchungsablauf etabliert und eine physikalische Therapie in die interdisziplinäre Tinnitustherapie integriert. Zur tinnitusmodulierenden Therapie muskulärer Triggerpunkte eignen sich neben Lokalanästhetika auch die Selbstmassage oder die Behandlung durch einen Physiotherapeuten oder Osteopathen.
    HNO 01/2008; 56(7). · 0.42 Impact Factor

Full-text (2 Sources)

Download
24 Downloads
Available from
May 20, 2014