Dorsal cochlear nucleus

Metrics details. The dorsal cochlear nucleus DCN is a region known to integrate somatosensory and auditory inputs and is identified as a potential key structure in the generation of phantom sound perception, especially noise-induced tinnitus. Yet, how altered homeostatic plasticity of the DCN induces and maintains the sensation of tinnitus is not clear, dorsal cochlear nucleus.

The dorsal cochlear nucleus DCN is the first site of multisensory integration in the auditory pathway of mammals. The DCN circuit integrates non-auditory information, such as head and ear position, with auditory signals, and this convergence may contribute to the ability to localize sound sources or to suppress perceptions of self-generated sounds. Several extrinsic sources of these non-auditory signals have been described in various species, and among these are first- and second-order trigeminal axonal projections. Trigeminal sensory signals from the face and ears could provide the non-auditory information that the DCN requires for its role in sound source localization and cancelation of self-generated sounds, for example, head and ear position or mouth movements that could predict the production of chewing or licking sounds. However, evidence for these projections in mice, an increasingly important species in auditory neuroscience, is lacking, raising questions about the universality of such proposed functions. We therefore investigated the presence of trigeminal projections to the DCN in mice, using viral and transgenic approaches. We found that the spinal trigeminal nucleus indeed projects to DCN, targeting granule cells and unipolar brush cells.

Dorsal cochlear nucleus

Federal government websites often end in. The site is secure. Author contributions: Z. The dorsal cochlear nucleus DCN is one of the first stations within the central auditory pathway where the basic computations underlying sound localization are initiated and heightened activity in the DCN may underlie central tinnitus. The neurotransmitter serotonin 5-hydroxytryptamine; 5-HT , is associated with many distinct behavioral or cognitive states, and serotonergic fibers are concentrated in the DCN. However, it remains unclear what is the function of this dense input. This excitatory effect results from an augmentation of hyperpolarization-activated cyclic nucleotide-gated channels I h or HCN channels. The serotonergic regulation of excitability is G-protein-dependent and involves cAMP and Src kinase signaling pathways. Moreover, optogenetic activation of serotonergic axon terminals increased excitability of fusiform cells. Our findings reveal that 5-HT exerts a potent influence on fusiform cells by altering their intrinsic properties, which may enhance the sensitivity of the DCN to sensory input. The serotonergic system modulates diverse physiological and behavioral functions, such as sleep, feeding, nociception, mood, and emotions Lucki, Serotonergic dysfunction has been implicated in a variety of psychiatric disorders, including depression, anxiety, schizophrenia, Parkinson's disease, and Alzheimer disease Meltzer et al.

December Learn how and when to remove this template message. The animals were placed in the restraining tube and left in the recording chamber for 5 min, allowing the animal to stay calm and stop exploring the chamber [ 72 ]. Figure 2, dorsal cochlear nucleus.

Federal government websites often end in. The site is secure. Tinnitus, the perception of a phantom sound, is a common consequence of damage to the auditory periphery. A major goal of tinnitus research is to find the loci of the neural changes that underlie the disorder. Crucial to this endeavor has been the development of an animal behavioral model of tinnitus, so that neural changes can be correlated with behavioral evidence of tinnitus.

The cochlear nuclear CN complex comprises two cranial nerve nuclei in the human brainstem , the ventral cochlear nucleus VCN and the dorsal cochlear nucleus DCN. The ventral cochlear nucleus is unlayered whereas the dorsal cochlear nucleus is layered. Auditory nerve fibers, fibers that travel through the auditory nerve also known as the cochlear nerve or eighth cranial nerve carry information from the inner ear, the cochlea , on the same side of the head, to the nerve root in the ventral cochlear nucleus. At the nerve root the fibers branch to innervate the ventral cochlear nucleus and the deep layer of the dorsal cochlear nucleus. All acoustic information thus enters the brain through the cochlear nuclei, where the processing of acoustic information begins. The outputs from the cochlear nuclei are received in higher regions of the auditory brainstem. The cochlear nuclei CN are located at the dorso-lateral side of the brainstem , spanning the junction of the pons and medulla. The major input to the cochlear nucleus is from the auditory nerve, a part of cranial nerve VIII the vestibulocochlear nerve.

Dorsal cochlear nucleus

The cochlear nuclei are a group of two small special sensory nuclei in the upper medulla for the cochlear nerve component of the vestibulocochlear nerve. They are part of the extensive cranial nerve nuclei within the brainstem. The dorsal and ventral nuclei are located in the dorsolateral upper medulla and are separated by the fibers of the inferior cerebellar peduncle :. From both nuclei, second-order sensory neurons project superiorly into the pons as part of the ascending auditory pathway. Cochlear afferent fibers enter the brainstem at the pontomedullary junction lateral to the facial nerve as part of the vestibulocochlear nerve. The nucleus houses the sensory cell bodies of the cochlear nerve which relay auditory information to the auditory components of the brainstem. Updating… Please wait. Unable to process the form. Check for errors and try again.

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Classic studies state that the structure of the primate DCN is quite different from that of rodents, with primates lacking granule cells, the recipients of somatosensory input. That technical issues may have been a factor in the human studies is reflected in the disagreement among the human studies. Comparative aspects of some features of the auditory system of primates. For whole-cell recordings, pipettes were filled with a solution containing the following in m m : K-gluconate, 9 HEPES, 2. All scripts used for controlling devices, stimulation control, and data analysis are available online LabScripts git repository, [ 76 ]. Middleton, S. Sections from the human brains were then treated with an antigen retrieval AR procedure. While this result is expected, it verifies the efficacy of the transsynaptic labeling approach. Wu C, Shore SE. J Pharmacol Exp Ther. However, the sources of multisensory information are not well understood, especially in mice, a species which has become an important model in auditory neuroscience. The fact that the sparse labeling of cells is not due to transsynaptic spread of virus is supported by the absence of somatic labeling within the regions of the trigeminal nuclei despite the presence of dense afferent fibers Figure 4. For loose cell-attached recordings, pipettes were filled with a normal ACSF solution.

Purpose: Eight lines of evidence implicating the dorsal cochlear nucleus DCN as a tinnitus contributing site are reviewed. We now expand the presentation of this model, elaborate on its essential details, and provide answers to commonly asked questions regarding its validity.

Dysfunction of the serotonergic system is implicated in the generation or perception of tinnitus Marriage and Barnes, ; Simpson and Davies, ; Salvinelli et al. The study of genetic polymorphisms related to serotonin in Alzheimer's disease: a new perspective in a heterogenic disorder. These data support the idea of a critical role for the DCN in mediating auditory-somatosensory interactions. This impression is confirmed by examination of the higher magnification image Fig. Singla, S. Yet, how altered homeostatic plasticity of the DCN induces and maintains the sensation of tinnitus is not clear. Fifty-micrometer-thick sections were made on a vibratome and saved as floating sections in PBS. Cochrane Database Syst Rev. We note that while the trigeminal ganglion was strongly labeled by this virus, auditory and vestibular ganglia were not labeled, either due to a lack of accessibility to the inner ear vasculature or due to specificity of the viral serotype. Their size heightens their sensitivity to small inputs and their location optimizes their ability to communicate with specific dendrites of DCN principal cells. It will be of interest to contrast the properties of SSCs in these structures with their counterparts in the electrosensory lobe of mormyrid electric fish, which share many of key features with the DCN Bell et al. We used 90dBSPL for 1h followed by 2h of silence, as we have previously shown to be able to generate tinnitus-like behavior without permanent threshold shifts [ 37 ]. Mouse methods and models for studies in hearing.