Dorsal cochlear nucleus

The dorsal cochlear nucleus DCN integrates auditory and multisensory dorsal cochlear nucleus at the earliest levels of auditory processing. Proposed roles for this region include sound localization in the vertical plane, head orientation to sounds of interest, dorsal cochlear nucleus, and suppression of sensitivity to expected sounds. Auditory and non-auditory information streams to the DCN are refined by a remarkably complex array of inhibitory and excitatory interneurons, and the role of each cell type is gaining increasing attention. One inhibitory neuron that has been poorly appreciated to date is the superficial stellate cell.

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. Mice were exposed to loud noise 9—11kHz, 90dBSPL, 1h, followed by 2h of silence , and auditory brainstem responses ABRs and gap prepulse inhibition of acoustic startle GPIAS were recorded 2 days before and 2 weeks after noise exposure to identify animals with a significantly decreased inhibition of startle, indicating tinnitus but without permanent hearing loss. We found that lowering DCN activity in mice displaying tinnitus-related behavior reduces tinnitus, but lowering DCN activity during noise exposure does not prevent noise-induced tinnitus.

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. Three major lines of evidence implicate the dorsal cochlear nucleus DCN in tinnitus. First, elevated spontaneous activity in the DCN is correlated with peripheral damage and tinnitus. Second, there are somatosensory inputs to the DCN that can modulate spontaneous activity and might mediate the somatic-auditory interactions seen in tinnitus patients. Third, we have found a subpopulation of DCN neurons in the adult rat that express doublecortin, a plasticity-related protein. The expression of this protein may reflect a role of these neurons in the neural reorganization causing tinnitus. However, there is a problem in extending the findings in the rodent DCN to humans.

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The dorsal cochlear nucleus DCN , also known as the " tuberculum acusticum " is a cortex-like structure on the dorso-lateral surface of the brainstem. Along with the ventral cochlear nucleus VCN , it forms the cochlear nucleus CN , where all auditory nerve fibers from the cochlea form their first synapses. The DCN differs from the ventral portion of the CN as it not only projects to the central nucleus a subdivision of the inferior colliculus CIC , but also receives efferent innervation from the auditory cortex , superior olivary complex and the inferior colliculus. The cytoarchitecture and neurochemistry of the DCN is similar to that of the cerebellum , an important concept in theories of DCN function. The pyramidal cells or giant cells are a major cell grouping of the DCN.

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.

Dorsal cochlear nucleus

Federal government websites often end in. The site is secure. Preview improvements coming to the PMC website in October Learn More or Try it out now. All data generated or analyzed during this study are included in this published article and supplementary information files. 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. Mice were exposed to loud noise 9—11kHz, 90dBSPL, 1h, followed by 2h of silence , and auditory brainstem responses ABRs and gap prepulse inhibition of acoustic startle GPIAS were recorded 2 days before and 2 weeks after noise exposure to identify animals with a significantly decreased inhibition of startle, indicating tinnitus but without permanent hearing loss.

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The particular physiology and morphology of each cochlear nucleus cell type enhances different aspects of sound information. Indeed, injection into trigeminal nuclei of tdTomato reporter mice of an anterogradely transported Cre-expressing virus capable of transsynaptic labeling led to robust expression of labeled fibers and cells in numerous known trigeminal targets, including trigeminal nuclei, thalamus, superior colliculus, facial nucleus, and cerebellum. The inset shows small, darkly labeled profiles, at arrow. GABAergic neural activity involved in salicylate-induced auditory cortex gain enhancement. Array programming with NumPy. Mugnaini et al. Eur Arch Otorhinolaryngol. Serotonin modulates auditory information processing in the cochlear nucleus of the rat. Hyperactivity in the dorsal cochlear nucleus after intense sound exposure and its resemblance to tone-evoked activity: a physiological model for tinnitus. An overview of mammalin auditory pathways with an emphasis on humans.

In normal individuals, phantom auditory sensations like tinnitus can develop during head, neck, and jaw muscle contractions Levine et al. In more than two thirds of people with chronic tinnitus, active and passive manipulations of these regions, such as jaw clenching or tensing the neck muscles, can alter the loudness, pitch, and location of the tinnitus Pinchoff et al.

In the second, groups of fusiform cells were activated following light exposure in slices taken from mice expressing channelrhodopsin2 ChR2 specifically in fusiform cells, which in turn drove action potentials in SSCs. The chinchilla is a New World rodent, and a member of the suborder Hysticognathi, whereas the rat is an Old World rodent and a member of a different suborder, Myomorpha. The site is secure. Figure 3. There are also many stained smaller somata. PHP-s virus has not been reported to jump across synapses and we do not suspect that these labeled cells are postsynaptic to primary afferents. A Sagittal section containing trigeminal nerve, trigeminal nucleus, and DCN. J Acoust Soc Am. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. Head, neck and eye movements that modulate tinnitus. Transient potassium currents regulate the discharge patterns of dorsal cochlear nucleus pyramidal cells. Middleton et al. Plasticity at glycinergic synapses in dorsal cochlear nucleus of rats with behavioral evidence of tinnitus. However, no primary trigeminal afferent fibers were apparent in cochlear nucleus, in contrast to a previous report in guinea pig Shore et al. The rectangle shows the location of the higher magnification image in B.