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inferior colliculus

Maike Vollmer, Ralph Eugene Beitel, Christoph E Schreiner, Patricia A Leake
In profoundly deaf cats, behavioral training with intracochlear electric stimulation (ICES) can improve temporal processing in the primary auditory cortex (AI). To investigate whether similar effects are manifest in the auditory midbrain, ICES was initiated in neonatally deafened cats either during development after short durations of deafness (8 wk of age) or in adulthood after long durations of deafness (≥3.5 yr). All of these animals received behaviorally-meaningless, 'passive' ICES. Some animals also received behavioral training with ICES...
October 12, 2016: Journal of Neurophysiology
Luli R Akinfiresoye, Clive Miranda, David M Lovinger, Prosper N'Gouemo
BACKGROUND: Cyclic AMP-dependent protein kinase A (PKA) signaling is a key target for the action of alcohol and may therefore play a role in the pathophysiology of alcohol withdrawal seizures (AWSs). Here, we investigated the role of PKA activity with respect to increased seizure susceptibility in rats that were subjected to alcohol withdrawal. METHODS: Adult male Sprague Dawley rats received 3 daily doses of ethanol (EtOH) (or vehicle) for 4 consecutive days. Rats were then tested for susceptibility to acoustically evoked AWSs 3, 24, and 48 hours after the last alcohol dose...
September 26, 2016: Alcoholism, Clinical and Experimental Research
D Hinova-Palova, B Landzhov, E Dzhambazova, L Edelstein, M Minkov, K Fakih, R Minkov, A Paloff, W Ovtscharoff
Using the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reaction with nitroblue tetrazolium, we provided a detailed investigation of the distribution, dimensional characteristics and morphology of NADPH-d-positive neurons in the three main subdivisions of the human inferior colliculus (IC): central nucleus, pericentral nucleus, and external nucleus. In accordance with their perikaryal diameter, dendritic and axonal morphology, these neurons were categorized as large (averaging up to 45 μm in diameter), medium (20-30 µm), small (13-16 µm) and very small (7-10 µm)...
September 19, 2016: Brain Structure & Function
Anna R Chambers, Juan J Salazar, Daniel B Polley
Neurons at higher stages of sensory processing can partially compensate for a sudden drop in peripheral input through a homeostatic plasticity process that increases the gain on weak afferent inputs. Even after a profound unilateral auditory neuropathy where >95% of afferent synapses between auditory nerve fibers and inner hair cells have been eliminated with ouabain, central gain can restore cortical processing and perceptual detection of basic sounds delivered to the denervated ear. In this model of profound auditory neuropathy, auditory cortex (ACtx) processing and perception recover despite the absence of an auditory brainstem response (ABR) or brainstem acoustic reflexes, and only a partial recovery of sound processing at the level of the inferior colliculus (IC), an auditory midbrain nucleus...
2016: Frontiers in Neural Circuits
Lara Li Hesse, Warren Bakay, Hui-Ching Ong, Lucy Anderson, Jonathan Ashmore, David McAlpine, Jennifer Linden, Roland Schaette
The occurrence of tinnitus can be linked to hearing loss in the majority of cases, but there is nevertheless a large degree of unexplained heterogeneity in the relation between hearing loss and tinnitus. Part of the problem might be that hearing loss is usually quantified in terms of increased hearing thresholds, which only provides limited information about the underlying cochlear damage. Moreover, noise exposure that does not cause hearing threshold loss can still lead to "hidden hearing loss" (HHL), i.e...
2016: Frontiers in Neurology
Alexander A Nevue, Richard A Felix, Christine V Portfors
Neuromodulators can alter the response properties of sensory neurons, including those in the auditory system. Dopamine, which plays a major role in reward and movement, has been shown to alter neural responses in the auditory brainstem and midbrain. Recently we identified the subparafascicular thalamic nucleus (SPF), part of the A11 dopaminergic cell group, as the source of dopamine to the inferior colliculus (IC). The superior olivary complex (SOC) is also a likely target of dopaminergic projections from the SPF because it receives projections from the SPF and contains fibers and terminals immunoreactive for tyrosine hydroxylase, the rate limiting enzyme in dopamine synthesis...
September 10, 2016: Hearing Research
Calum Alex Grimsley, David Brian Green, Shobhana Sivaramakrishnan
The coding of sound level by ensembles of neurons improves the accuracy with which listeners identify how loud a sound is. In the auditory system, the rate at which neurons fire in response to changes in sound level is shaped by local networks. Voltage-gated conductances alter local output by regulating neuronal firing, but their role in modulating responses to sound level is unclear. Here, we tested the effects of L-type calcium channels (CaL: CaV1.1-1.4) on sound level coding in the central nucleus of the inferior colliculus (ICC), in the auditory midbrain...
September 7, 2016: Journal of Neurophysiology
P Medeiros, R L de Freitas, M O Silva, N C Coimbra, L Melo-Thomas
The inferior colliculus (IC), a midbrain structure that processes acoustic information of aversive nature, is distinguished from other auditory nuclei in the brainstem by its connections with structures of the motor system. Previous evidence relating the IC to motor behavior shows that glutamatergic and GABAergic mechanisms in the IC exert influence on systemic haloperidol-induced catalepsy. There is substantial evidence supporting a role played by the endocannabinoid system as a modulator of the glutamatergic neurotransmission, as well as the dopaminergic activity in the basal nuclei and therefore it may be considered as a potential pharmacological target for the treatment of movement disorders...
September 3, 2016: Neuroscience
Jasper V Smit, Marcus L F Janssen, Gusta van Zwieten, Ali Jahanshahi, Yasin Temel, Robert J Stokroos
In animal models of tinnitus pathological neuronal activity has been demonstrated. Deep brain stimulation disrupts pathological neuronal activity and might therefore be a potential treatment for patients who suffer severely from tinnitus. In this study, the effect of DBS in the inferior colliculi is investigated in an animal model of tinnitus. The external cortex of the inferior colliculus was targeted because of the key position of the inferior colliculus within the auditory network and the relation of the external cortex with the limbic system...
November 1, 2016: Brain Research
Alexander Dee, Kairong Li, Xin Heng, Qiuxia Guo, James Y H Li
During embryogenesis, the tectum (dorsal midbrain) displays gradients in both gene expression and cytogenesis along the anteroposterior axis, and eventually produces the superior colliculus anteriorly and inferior colliculus posteriorly. Although it is known that different strengths and durations of FGF signaling control the developmental gradient and cell fate decision in the developing tectum, the underlying mechanism and signaling cascade downstream of FGF remains unclear. Here, we showed that deleting Shp2, which links FGF with the ERK pathway, prevented inferior colliculus formation by depleting a previously uncharacterized stem cell zone, designated as tectal stem zone, in the posterior part of the developing tectum...
August 30, 2016: Development
Rüdiger Land, Alice Burghard, Andrej Kral
In mice, the auditory brainstem response (ABR) is frequently used to assess hearing status in transgenic hearing models. The diagnostic value of the ABR depends on knowledge about the anatomical sources of its characteristic waves. Here, we studied the contribution of the inferior colliculus (IC) to the click-evoked scalp ABR in mice. We demonstrate a non-invasive correlate of the IC response that can be measured in the scalp ABR as a slow positive wave P0 with peak latency 7-8 ms when recorded with adequate band-pass filtering...
August 22, 2016: Hearing Research
Mili B Patel, Stacy Sons, Georgiy Yudintsev, Alexandria M H Lesicko, Luye Yang, Gehad A Taha, Scott M Pierce, Daniel A Llano
Descending projections from the thalamus and related structures to the midbrain are evolutionarily highly conserved. However, the basic organization of this auditory thalamotectal pathway has not yet been characterized. The purpose of this study was to obtain a better understanding of the anatomical and neurochemical features of this pathway. Analysis of the distributions of retrogradely labeled cells after focal injections of retrograde tracer into the inferior colliculus (IC) of the mouse revealed that most of the subcortical descending projections originated in the brachium of the IC and the paralaminar portions of the auditory thalamus...
August 25, 2016: Journal of Comparative Neurology
Hisataka Fujimoto, Kotaro Konno, Masahiko Watanabe, Shozo Jinno
The inferior colliculus (IC) is partitioned into three subdivisions: the dorsal and lateral cortices (DC and LC) and the central nucleus (ICC), and serves as an integration center of auditory information. Recent studies indicate that a certain population of IC neurons may represent the non-GABAergic phenotype, while they express well-established cortical/hippocampal GABAergic neuron markers. In this study, we used the optical disector to investigate the phenotype of IC neurons expressing parvalbumin (PV) and/or nitric oxide synthase (NOS) in C57BL/6J mice during the late postnatal period...
August 25, 2016: Journal of Comparative Neurology
Craig A Atencio, Victor Shen, Christoph E Schreiner
The central nucleus of the inferior colliculus (ICC) contains a laminar structure that functions as an organizing substrate of ascending inputs and local processing. While topographic distributions of ICC response parameters within and across laminae have been reported, the functional micro-organization of the ICC is less well understood. For pairs of neighboring ICC neurons, we examined the nature of functional connectivity and receptive field preferences to gain a better understanding of the structure and function of local circuits...
October 29, 2016: Neuroscience
Lina Yassin, Michael Pecka, Jasmin Kajopoulos, Helge Gleiss, Lu Li, Christian Leibold, Felix Felmy
The identification and characterization of organization principals is essential for the understanding of neural function of brain areas. The inferior colliculus (IC) represents a midbrain nexus involved in numerous aspects of auditory processing. Likewise, neurons throughout the IC are tuned to a diverse range of specific stimulus features. Yet beyond a topographic arrangement of the cochlea-inherited frequency tuning, the functional organization of the IC is not well understood. Particularly, a common principle that links the diverse tuning characteristics is unknown...
August 17, 2016: Hearing Research
Giedre Milinkeviciute, Michael A Muniak, David K Ryugo
Ascending projections of the dorsal cochlear nucleus (DCN) primarily target the contralateral inferior colliculus (IC). In turn, the IC sends bilateral descending projections back to the DCN. We sought to determine the nature of these descending axons in order to infer circuit mechanisms of signal processing at one of the earliest stages of the central auditory pathway. An anterograde tracer was injected in the IC of CBA/Ca mice to reveal terminal characteristics of the descending axons. Retrograde tracer deposits were made in the DCN of CBA/Ca and transgenic GAD67-EGFP mice to investigate the cells giving rise to these projections...
August 11, 2016: Journal of Comparative Neurology
Ankur Joshi, Bopanna I Kalappa, Charles T Anderson, Thanos Tzounopoulos
UNLABELLED: The neuromodulator acetylcholine (ACh) is crucial for several cognitive functions, such as perception, attention, and learning and memory. Whereas, in most cases, the cellular circuits or the specific neurons via which ACh exerts its cognitive effects remain unknown, it is known that auditory cortex (AC) neurons projecting from layer 5B (L5B) to the inferior colliculus, corticocollicular neurons, are required for cholinergic-mediated relearning of sound localization after occlusion of one ear...
August 10, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Songbai Yang, Zhigang Mei, Lingjing Tan, Wenhan Ma, Dingqi Zhang, Zhaojun Wang, Tiantian Li, Kunyan Huang, Sanjin Cai
OBJECTIVE: To explore the effects of electrical stimulation at acupoints in the distribution area of auricular vagus nerve combined with sound masking on auditory brainstem response (ABR) and contents of neurotransmitters of γ-aminobutyric acid (γ-GABA), 5-hydroxytryptamine (5-HT) and acetyl choline (Ach) in inferior colliculus of tinnitus rats. METHODS: Twenty-four male adult SD rats were randomized into a control group, a model group, a 7-d treatment group and a 15-d treatment group...
May 2016: Zhongguo Zhen Jiu, Chinese Acupuncture & Moxibustion
Vijayakumar Chinnadurai, C M Sreedhar, Subash Khushu
OBJECTIVE: The use of diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI) was evaluated in assessing cochlear nerve deficiency (CND) and its effect on normal maturation of auditory tract. METHODS: 25 CND patients and 25 controls (age matched: 2months to 17years, gender matched) were evaluated by mean kurtosis (MK), axial kurtosis, and radial kurtosis and compared against fractional anisotropy (FA), axial and radial diffusivities in internal auditory canal (IAC), lateral lemniscus (LL) and inferior colliculus (IC)...
November 2016: Magnetic Resonance Imaging
Kimberly E Miller, Kaitlyn Barr, Mitchell Krawczyk, Ellen Covey
Eptesicus fuscus is typical of temperate zone bats in that both sexes undergo marked seasonal changes in behavior, endocrine status, and reproductive status. Acoustic communication plays a key role in many seasonal behaviors. For example, males emit specialized vocalizations during mating in the fall, and females use different specialized vocalizations to communicate with infants in late spring. Bats of both sexes use echolocation for foraging during times of activity, but engage in little sound-directed behavior during torpor and hibernation in winter...
July 26, 2016: Hearing Research
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