1
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Tan HT, Smith PF, Zheng Y. Time-dependent effects of acoustic trauma and tinnitus on extracellular levels of amino acids in the inferior colliculus of rats. Hear Res 2024; 443:108948. [PMID: 38219615 DOI: 10.1016/j.heares.2024.108948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 12/19/2023] [Accepted: 01/02/2024] [Indexed: 01/16/2024]
Abstract
Chronic tinnitus is a debilitating condition with very few management options. Acoustic trauma that causes tinnitus has been shown to induce neuronal hyperactivity in multiple brain areas in the auditory pathway, including the inferior colliculus. This neuronal hyperactivity could be attributed to an imbalance between excitatory and inhibitory neurotransmission. However, it is not clear how the levels of neurotransmitters, especially neurotransmitters in the extracellular space, change over time following acoustic trauma and the development of tinnitus. In the present study, a range of amino acids were measured in the inferior colliculus of rats during acoustic trauma as well as at 1 week and 5 months post-trauma using in vivo microdialysis and high-performance liquid chromatography. Amino acid levels in response to sound stimulation were also measured at 1 week and 5 months post-trauma. It was found that unilateral exposure to a 16 kHz pure tone at 115 dB SPL for 1 h caused immediate hearing loss in all the animals and chronic tinnitus in 58 % of the animals. Comparing to the sham condition, extracellular levels of GABA were significantly increased at both the acute and 1 week time points after acoustic trauma. However, there was no significant difference in any of the amino acid levels measured between sham, tinnitus positive and tinnitus negative animals at 5 months post-trauma. There was also no clear pattern in the relationship between neurochemical changes and sound frequency/acoustic trauma/tinnitus status, which might be due to the relatively poorer temporal resolution of the microdialysis compared to electrophysiological responses.
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Affiliation(s)
- Huey Tieng Tan
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand; Eisdell Moore Centre for Research on Hearing and Balance Disorders, University of Auckland, New Zealand
| | - Paul F Smith
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand; Eisdell Moore Centre for Research on Hearing and Balance Disorders, University of Auckland, New Zealand
| | - Yiwen Zheng
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand; Eisdell Moore Centre for Research on Hearing and Balance Disorders, University of Auckland, New Zealand.
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2
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Offutt SJ, Rose JE, Crawford KJ, Harris ML, Lim HH. Gradients of response latencies and temporal precision of auditory neurons extend across the whole inferior colliculus. J Neurophysiol 2023; 130:719-735. [PMID: 37609690 PMCID: PMC10650646 DOI: 10.1152/jn.00461.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 08/07/2023] [Accepted: 08/08/2023] [Indexed: 08/24/2023] Open
Abstract
Neural responses to acoustic stimulation have long been studied throughout the auditory system to understand how sound information is coded for perception. Within the inferior colliculus (IC), a majority of the studies have focused predominantly on characterizing neural responses within the central region (ICC), as it is viewed as part of the lemniscal system mainly responsible for auditory perception. In contrast, the responses of outer cortices (ICO) have largely been unexplored, though they also function in auditory perception tasks. Therefore, we sought to expand on previous work by completing a three-dimensional (3-D) functional mapping study of the whole IC. We analyzed responses to different pure tone and broadband noise stimuli across all IC subregions and correlated those responses with over 2,000 recording locations across the IC. Our study revealed there are well-organized trends for temporal response parameters across the full IC that do not show a clear distinction at the ICC and ICO border. These gradients span from slow, imprecise responses in the caudal-medial IC to fast, precise responses in the rostral-lateral IC, regardless of subregion, including the fastest responses located in the ICO. These trends were consistent at various acoustic stimulation levels. Weaker spatial trends could be found for response duration and spontaneous activity. Apart from tonotopic organization, spatial trends were not apparent for spectral response properties. Overall, these detailed acoustic response maps across the whole IC provide new insights into the organization and function of the IC.NEW & NOTEWORTHY Study of the inferior colliculus (IC) has largely focused on the central nucleus, with little exploration of the outer cortices. Here, we systematically assessed the acoustic response properties from over 2,000 locations in different subregions of the IC. The results revealed spatial trends in temporal response patterns that span all subregions. Furthermore, two populations of temporal response types emerged for neurons in the outer cortices that may contribute to their functional roles in auditory tasks.
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Affiliation(s)
- Sarah J Offutt
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States
| | - Jessica E Rose
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States
| | - Kellie J Crawford
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States
| | - Megan L Harris
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States
| | - Hubert H Lim
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States
- Department of Otolaryngology, Head and Neck Surgery, University of Minnesota, Minneapolis, Minnesota, United States
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota, United States
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3
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Liu Y, Li Y, Peng Y, Yu H, Xiao Z. Bilateral Interactions in the Mouse Dorsal Inferior Colliculus Enhance the Ipsilateral Neuronal Responses and Binaural Hearing. Front Physiol 2022; 13:854077. [PMID: 35514328 PMCID: PMC9061965 DOI: 10.3389/fphys.2022.854077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 04/01/2022] [Indexed: 11/13/2022] Open
Abstract
The inferior colliculus (IC) is a critical centre for the binaural processing of auditory information. However, previous studies have mainly focused on the central nucleus of the inferior colliculus (ICC), and less is known about the dorsal nucleus of the inferior colliculus (ICD). Here, we first examined the characteristics of the neuronal responses in the mouse ICD and compared them with those in the inferior colliculus under binaural and monaural conditions using in vivo loose-patch recordings. ICD neurons exhibited stronger responses to ipsilateral sound stimulation and better binaural summation than those of ICC neurons, which indicated a role for the ICD in binaural hearing integration. According to the abundant interactions between bilateral ICDs detected using retrograde virus tracing, we further studied the effect of unilateral ICD silencing on the contralateral ICD. After lidocaine was applied, the responses of some ICD neurons (13/26), especially those to ipsilateral auditory stimuli, decreased. Using whole-cell recording and optogenetic methods, we investigated the underlying neuronal circuits and synaptic mechanisms of binaural auditory information processing in the ICD. The unilateral ICD provides both excitatory and inhibitory projections to the opposite ICD, and the advantaged excitatory inputs may be responsible for the enhanced ipsilateral responses and binaural summation of ICD neurons. Based on these results, the contralateral ICD might modulate the ipsilateral responses of the neurons and binaural hearing.
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Affiliation(s)
| | | | | | | | - Zhongju Xiao
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
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4
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Sitek KR, Calabrese E, Johnson GA, Ghosh SS, Chandrasekaran B. Structural Connectivity of Human Inferior Colliculus Subdivisions Using in vivo and post mortem Diffusion MRI Tractography. Front Neurosci 2022; 16:751595. [PMID: 35392412 PMCID: PMC8981148 DOI: 10.3389/fnins.2022.751595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 01/27/2022] [Indexed: 12/05/2022] Open
Abstract
Inferior colliculus (IC) is an obligatory station along the ascending auditory pathway that also has a high degree of top-down convergence via efferent pathways, making it a major computational hub. Animal models have attributed critical roles for the IC in in mediating auditory plasticity, egocentric selection, and noise exclusion. IC contains multiple functionally distinct subdivisions. These include a central nucleus that predominantly receives ascending inputs and external and dorsal nuclei that receive more heterogeneous inputs, including descending and multisensory connections. Subdivisions of human IC have been challenging to identify and quantify using standard brain imaging techniques such as MRI, and the connectivity of each of these subnuclei has not been identified in the human brain. In this study, we estimated the connectivity of human IC subdivisions with diffusion MRI (dMRI) tractography, using both anatomical-based seed analysis as well as unsupervised k-means clustering. We demonstrate sensitivity of tractography to overall IC connections in both high resolution post mortem and in vivo datasets. k-Means clustering of the IC streamlines in both the post mortem and in vivo datasets generally segregated streamlines based on their terminus beyond IC, such as brainstem, thalamus, or contralateral IC. Using fine-grained anatomical segmentations of the major IC subdivisions, the post mortem dataset exhibited unique connectivity patterns from each subdivision, including commissural connections through dorsal IC and lateral lemniscal connections to central and external IC. The subdivisions were less distinct in the context of in vivo connectivity, although lateral lemniscal connections were again highest to central and external IC. Overall, the unsupervised and anatomically driven methods provide converging evidence for distinct connectivity profiles for each of the IC subdivisions in both post mortem and in vivo datasets, suggesting that dMRI tractography with high quality data is sensitive to neural pathways involved in auditory processing as well as top-down control of incoming auditory information.
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Affiliation(s)
- Kevin R. Sitek
- SoundBrain Lab, Brain and Auditory Sciences Research Initiative, Department of Communication and Science Disorders, University of Pittsburgh, Pittsburgh, PA, United States
- *Correspondence: Kevin R. Sitek,
| | - Evan Calabrese
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States
| | - G. Allan Johnson
- Center for In Vivo Microscopy, Duke University, Durham, NC, United States
| | - Satrajit S. Ghosh
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, United States
- Department of Otolaryngology – Head and Neck Surgery, Harvard Medical School, Boston, MA, United States
| | - Bharath Chandrasekaran
- SoundBrain Lab, Brain and Auditory Sciences Research Initiative, Department of Communication and Science Disorders, University of Pittsburgh, Pittsburgh, PA, United States
- Bharath Chandrasekaran,
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5
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Zhang L, Hernandez VS, Gerfen CR, Jiang SZ, Zavala L, Barrio RA, Eiden LE. Behavioral role of PACAP signaling reflects its selective distribution in glutamatergic and GABAergic neuronal subpopulations. eLife 2021; 10:61718. [PMID: 33463524 PMCID: PMC7875564 DOI: 10.7554/elife.61718] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 01/18/2021] [Indexed: 01/25/2023] Open
Abstract
The neuropeptide PACAP, acting as a co-transmitter, increases neuronal excitability, which may enhance anxiety and arousal associated with threat conveyed by multiple sensory modalities. The distribution of neurons expressing PACAP and its receptor, PAC1, throughout the mouse nervous system was determined, in register with expression of glutamatergic and GABAergic neuronal markers, to develop a coherent chemoanatomical picture of PACAP role in brain motor responses to sensory input. A circuit role for PACAP was tested by observing Fos activation of brain neurons after olfactory threat cue in wild-type and PACAP knockout mice. Neuronal activation and behavioral response, were blunted in PACAP knock-out mice, accompanied by sharply downregulated vesicular transporter expression in both GABAergic and glutamatergic neurons expressing PACAP and its receptor. This report signals a new perspective on the role of neuropeptide signaling in supporting excitatory and inhibitory neurotransmission in the nervous system within functionally coherent polysynaptic circuits.
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Affiliation(s)
- Limei Zhang
- Department of Physiology, Faculty of Medicine, National Autonomous University of Mexico, Mexico City, Mexico.,Section on Molecular Neuroscience, National Institute of Mental Health, Intramural Research Program, Bethesda, United States
| | - Vito S Hernandez
- Department of Physiology, Faculty of Medicine, National Autonomous University of Mexico, Mexico City, Mexico
| | - Charles R Gerfen
- Laboratory of Systems Neuroscience, National Institute of Mental Health, Intramural Research Program, Bethesda, United States
| | - Sunny Z Jiang
- Section on Molecular Neuroscience, National Institute of Mental Health, Intramural Research Program, Bethesda, United States
| | - Lilian Zavala
- Department of Physiology, Faculty of Medicine, National Autonomous University of Mexico, Mexico City, Mexico
| | - Rafael A Barrio
- Section on Molecular Neuroscience, National Institute of Mental Health, Intramural Research Program, Bethesda, United States.,Department of Complex Systems, Institute of Physics, National Autonomous University of Mexico (UNAM), Mexico, Mexico
| | - Lee E Eiden
- Section on Molecular Neuroscience, National Institute of Mental Health, Intramural Research Program, Bethesda, United States
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6
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Changes in microRNA Expression in the Cochlear Nucleus and Inferior Colliculus after Acute Noise-Induced Hearing Loss. Int J Mol Sci 2020; 21:ijms21228792. [PMID: 33233709 PMCID: PMC7709026 DOI: 10.3390/ijms21228792] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 11/17/2022] Open
Abstract
Noise-induced hearing loss (NIHL) can lead to secondary changes that induce neural plasticity in the central auditory pathway. These changes include decreases in the number of synapses, the degeneration of auditory nerve fibers, and reorganization of the cochlear nucleus (CN) and inferior colliculus (IC) in the brain. This study investigated the role of microRNAs (miRNAs) in the neural plasticity of the central auditory pathway after acute NIHL. Male Sprague–Dawley rats were exposed to white band noise at 115 dB for 2 h, and the auditory brainstem response (ABR) and morphology of the organ of Corti were evaluated on days 1 and 3. Following noise exposure, the ABR threshold shift was significantly smaller in the day 3 group, while wave II amplitudes were significantly larger in the day 3 group compared to the day 1 group. The organ of Corti on the basal turn showed evidence of damage and the number of surviving outer hair cells was significantly lower in the basal and middle turn areas of the hearing loss groups relative to controls. Five and three candidate miRNAs for each CN and IC were selected based on microarray analysis and quantitative reverse transcription PCR (RT-qPCR). The data confirmed that even short-term acoustic stimulation can lead to changes in neuroplasticity. Further studies are needed to validate the role of these candidate miRNAs. Such miRNAs may be used in the early diagnosis and treatment of neural plasticity of the central auditory pathway after acute NIHL.
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7
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Cheng L, Guo ZY, Qu YL. Cross-modality modulation of auditory midbrain processing of intensity information. Hear Res 2020; 395:108042. [PMID: 32810721 DOI: 10.1016/j.heares.2020.108042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 06/12/2020] [Accepted: 07/08/2020] [Indexed: 02/03/2023]
Abstract
In nature, animals constantly receive a multitude of sensory stimuli, such as visual, auditory, and somatosensory. The integration across sensory modalities is advantageous for the precise processing of sensory inputs which is essential for animals to survival. Although some principles of cross-modality integration have been revealed by many studies, little insight has been gained into its functional potentials. In this study, the functional influence of cross-modality modulation on auditory processing of intensity information was investigated via recording neuronal activity in the auditory midbrain (i.e., inferior colliculus, IC) under the conditions of visual, auditory, and audiovisual stimuli, respectively. Results demonstrated that combined audiovisual stimuli either enhanced or suppressed the responses of IC neurons compared to auditory stimuli alone, even though the same visual stimuli alone induced no response. Audiovisual modulation appeared to be strongest when the combined audiovisual stimuli were located at the best auditory azimuth of neurons as well as when presented with intensity at near-threshold levels. Additionally, the rate-intensity function of IC neurons to auditory stimuli was expanded or compressed by audiovisual modulation, which was highly dependent on the minimal threshold (MT) of neurons. Lowering of the MT and greater audiovisual modulation for the neuron indicated an intensity-specific enhancement of auditory intensity sensitivity by cross-modality modulation. Overall, evidence suggests a potential functional role of cross-modality modulation in IC that serves to instruct adaptive plasticity to enhance the auditory perception of intensity information.
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Affiliation(s)
- Liang Cheng
- School of Psychology & Key Laboratory of Adolescent Cyberpsycology and Behavior (CCNU) of Ministry of Education, Central China Normal University, Wuhan, 430079, China; School of Life Sciences & Hubei Key Lab of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, 430079, China.
| | - Zhao-Yang Guo
- School of Psychology & Key Laboratory of Adolescent Cyberpsycology and Behavior (CCNU) of Ministry of Education, Central China Normal University, Wuhan, 430079, China
| | - Yi-Li Qu
- School of Psychology & Key Laboratory of Adolescent Cyberpsycology and Behavior (CCNU) of Ministry of Education, Central China Normal University, Wuhan, 430079, China
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8
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Ito T. Different coding strategy of sound information between GABAergic and glutamatergic neurons in the auditory midbrain. J Physiol 2020; 598:1039-1072. [DOI: 10.1113/jp279296] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 01/13/2020] [Indexed: 12/19/2022] Open
Affiliation(s)
- Tetsufumi Ito
- Department of AnatomyKanazawa Medical University Uchinada Ishikawa 920‐0293 Japan
- Research and Education Program for Life ScienceUniversity of Fukui Fukui Fukui 910‐8507 Japan
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9
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Ono M, Bishop DC, Oliver DL. Neuronal sensitivity to the interaural time difference of the sound envelope in the mouse inferior colliculus. Hear Res 2019; 385:107844. [PMID: 31759235 DOI: 10.1016/j.heares.2019.107844] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/28/2019] [Accepted: 11/10/2019] [Indexed: 12/14/2022]
Abstract
We examined the sensitivity of the neurons in the mouse inferior colliculus (IC) to the interaural time differences (ITD) conveyed in the sound envelope. Utilizing optogenetic methods, we compared the responses to the ITD in the envelope of identified glutamatergic and GABAergic neurons. More than half of both cell types were sensitive to the envelope ITD, and the ITD curves were aligned at their troughs. Within the physiological ITD range of mice (±50 μs), the ITD curves of both cell types had a higher firing rate when the contralateral envelope preceded the ipsilateral envelope. These results show that the circuitry to process ITD persists in the mouse despite its lack of low-frequency hearing. The sensitivity of IC neurons to ITD is most likely to be shaped by the binaural interaction of excitation and inhibition in the lateral superior olive.
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Affiliation(s)
- Munenori Ono
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA, 06030-3401; Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan.
| | - Deborah C Bishop
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA, 06030-3401
| | - Douglas L Oliver
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, USA, 06030-3401
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10
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Kitagawa M, Sakaba T. Developmental changes in the excitatory short‐term plasticity at input synapses in the rat inferior colliculus. Eur J Neurosci 2019; 50:2830-2846. [DOI: 10.1111/ejn.14422] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 03/28/2019] [Accepted: 04/04/2019] [Indexed: 11/29/2022]
Affiliation(s)
- Mako Kitagawa
- Graduate School of Brain Science Doshisha University Kyoto Japan
| | - Takeshi Sakaba
- Graduate School of Brain Science Doshisha University Kyoto Japan
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11
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Ono M, Ito T. Inhibitory Neural Circuits in the Mammalian Auditory Midbrain. J Exp Neurosci 2018; 12:1179069518818230. [PMID: 30559596 PMCID: PMC6291857 DOI: 10.1177/1179069518818230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 11/15/2018] [Indexed: 01/12/2023] Open
Abstract
The auditory midbrain is the critical integration center in the auditory pathway of vertebrates. Synaptic inhibition plays a key role during information processing in the auditory midbrain, and these inhibitory neural circuits are seen in all vertebrates and are likely essential for hearing. Here, we review the structure and function of the inhibitory neural circuits of the auditory midbrain. First, we provide an overview on how these inhibitory circuits are organized within different clades of vertebrates. Next, we focus on recent findings in the mammalian auditory midbrain, the most studied of the vertebrates, and discuss how the mammalian auditory midbrain is functionally coordinated.
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Affiliation(s)
- Munenori Ono
- Department of Physiology, School of Medicine, Kanazawa Medical University, Uchinada, Japan
| | - Tetsufumi Ito
- Department of Anatomy, School of Medicine, Kanazawa Medical University, Uchinada, Japan
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12
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Ito T, Furuyama T, Hase K, Kobayasi KI, Hiryu S, Riquimaroux H. Organization of subcortical auditory nuclei of Japanese house bat (Pipistrellus abramus) identified with cytoarchitecture and molecular expression. J Comp Neurol 2018; 526:2824-2844. [PMID: 30168138 DOI: 10.1002/cne.24529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 08/23/2018] [Accepted: 08/25/2018] [Indexed: 11/09/2022]
Abstract
The auditory system of echolocating bats shows remarkable specialization likely related to analyzing echoes of sonar pulses. However, significant interspecies differences have been observed in the organization of auditory pathways among echolocating bats, and the homology of auditory nuclei with those of non-echolocating species has not been established. Here, in order to establish the homology and specialization of auditory pathways in echolocating bats, the expression of markers for glutamatergic, GABAergic, and glycinergic phenotypes in the subcortical auditory nuclei of Japanese house bat (Pipistrellus abramus) was evaluated. In the superior olivary complex, we identified the medial superior olive and superior paraolivary nuclei as expressing glutamatergic and GABAergic phenotypes, respectively, suggesting these nuclei are homologous with those of rodents. In the nuclei of the lateral lemniscus (NLL), the dorsal nucleus was found to be purely GABAergic, the intermediate nucleus was a mixture of glutamatergic and inhibitory neurons, the compact part of the ventral nucleus was purely glycinergic, and the multipolar part of the ventral nucleus expressed both GABA and glycine. In the inferior colliculus (IC), the central nucleus was found to be further subdivided into dorsal and ventral parts according to differences in the density of terminals and the morphology of large GABAergic neurons, suggesting specialization to sonar pulse structure. Medial geniculate virtually lacked GABAergic neurons, suggesting that the organization of the tectothalamic pathway is similar with that of rodents. Taken together, our findings revealed that specialization primarily occurs with regard to nuclei size and organization of the NLL and IC.
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Affiliation(s)
- Tetsufumi Ito
- Department of Anatomy, Kanazawa Medical University, Uchinada, Ishikawa, Japan.,Research and Education Program for Life Science, University of Fukui, Fukui, Fukui, Japan
| | - Takafumi Furuyama
- Neuroethology and Bioengineering Laboratory, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Kazuma Hase
- Neuroethology and Bioengineering Laboratory, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Kohta I Kobayasi
- Neuroethology and Bioengineering Laboratory, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Shizuko Hiryu
- Neuroethology and Bioengineering Laboratory, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan
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13
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He N, Kong L, Lin T, Wang S, Liu X, Qi J, Yan J. Diversity of bilateral synaptic assemblies for binaural computation in midbrain single neurons. Hear Res 2017; 355:54-63. [DOI: 10.1016/j.heares.2017.09.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 09/12/2017] [Accepted: 09/14/2017] [Indexed: 10/18/2022]
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14
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Lee JK, Kim MJ. The distribution of calbindin-D28k, parvalbumin, and calretinin immunoreactivity in the inferior colliculus of circling mouse. Anat Cell Biol 2017; 50:230-238. [PMID: 29043102 PMCID: PMC5639178 DOI: 10.5115/acb.2017.50.3.230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 07/24/2017] [Accepted: 07/26/2017] [Indexed: 11/27/2022] Open
Abstract
The circling mice with tmie gene mutation are known as an animal deafness model, which showed hyperactive circling movement. Recently, the reinvestigation of circling mouse was performed to check the inner ear pathology as a main lesion of early hearing loss. In this trial, the inner ear organs were not so damaged to cause the hearing deficit of circling (cir/cir) mouse at 18 postnatal day (P18) though auditory brainstem response data indicated hearing loss of cir/cir mice at P18. Thus, another mechanism may be correlated with the early hearing loss of cir/cir mice at P18. Hearing loss in the early life can disrupt the ascending and descending information to inferior colliculus (IC) as integration site. There were many reports that hearing loss could result in the changes in Ca2+ concentration by either cochlear ablation or genetic defect. However, little was known to be reported about the correlation between the pathology of IC and Ca2+ changes in circling mice. Therefore, the present study investigated the distribution of calcium-binding proteins (CaBPs), calbindin-D28k, parvalbumin, and calretinin immunoreactivity (IR) in the IC to compare among wild-type (+/+), heterozygous (+/cir), and homozygous (cir/cir) mice by immunohistochemistry. The decreases of CaBPs IR in cir/cir were statistically significant in the neurons as well as neuropil of IC. Thus, this study proposed overall distributional alteration of CaBPs IR in the IC caused by early hearing defect and might be helpful to elucidate the pathology of central auditory disorder related with Ca2+ metabolism.
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Affiliation(s)
- Jin-Koo Lee
- Department of Pharmacology, Dankook University College of Medicine, Cheonan, Korea
| | - Myeung Ju Kim
- Department of Anatomy, Dankook University College of Medicine, Cheonan, Korea
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15
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Identified GABAergic and Glutamatergic Neurons in the Mouse Inferior Colliculus Share Similar Response Properties. J Neurosci 2017; 37:8952-8964. [PMID: 28842411 DOI: 10.1523/jneurosci.0745-17.2017] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 07/19/2017] [Accepted: 08/05/2017] [Indexed: 12/13/2022] Open
Abstract
GABAergic neurons in the inferior colliculus (IC) play a critical role in auditory information processing, yet their responses to sound are unknown. Here, we used optogenetic methods to characterize the response properties of GABAergic and presumed glutamatergic neurons to sound in the IC. We found that responses to pure tones of both inhibitory and excitatory classes of neurons were similar in their thresholds, response latencies, rate-level functions, and frequency tuning, but GABAergic neurons may have higher spontaneous firing rates. In contrast to their responses to pure tones, the inhibitory and excitatory neurons differed in their ability to follow amplitude modulations. The responses of both cell classes were affected by their location regardless of the cell type, especially in terms of their frequency tuning. These results show that the synaptic domain, a unique organization of local neural circuits in the IC, may interact with all types of neurons to produce their ultimate response to sound.SIGNIFICANCE STATEMENT Although the inferior colliculus (IC) in the auditory midbrain is composed of different types of neurons, little is known about how these specific types of neurons respond to sound. Here, for the first time, we characterized the response properties of GABAergic and glutamatergic neurons in the IC. Both classes of neurons had diverse response properties to tones but were overall similar, except for the spontaneous activity and their ability to follow amplitude-modulated sound. Both classes of neurons may compose a basic local circuit that is replicated throughout the IC. Within each local circuit, the inputs to the local circuit may have a greater influence in determining the response properties to sound than the specific neuron types.
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16
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Ito T, Atoji Y. Tectothalamic inhibitory projection neurons in the avian torus semicircularis. J Comp Neurol 2016; 524:2604-22. [DOI: 10.1002/cne.23979] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 01/26/2016] [Accepted: 01/27/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Tetsufumi Ito
- Department of Anatomy; Faculty of Medical Sciences, University of Fukui; Eiheiji Fukui 910-1193 Japan
- Research and Education Program for Life Science, University of Fukui; Fukui Fukui 910-8507 Japan
| | - Yasuro Atoji
- Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University; Yanagido Gifu 501-1193 Japan
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Ito T, Bishop DC, Oliver DL. Functional organization of the local circuit in the inferior colliculus. Anat Sci Int 2015; 91:22-34. [PMID: 26497006 DOI: 10.1007/s12565-015-0308-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 10/05/2015] [Indexed: 01/12/2023]
Abstract
The inferior colliculus (IC) is the first integration center of the auditory system. After the transformation of sound to neural signals in the cochlea, the signals are analyzed by brainstem auditory nuclei that, in turn, transmit this information to the IC. However, the neural circuitry that underlies this integration is unclear. This review consists of two parts: one is about the cell type which is likely to integrate sound information, and the other is about a technique which is useful for studying local circuitry. Large GABAergic (LG) neurons receive dense excitatory axosomatic terminals that originate from the lower brainstem auditory nuclei as well as local IC neurons. Dozens of axons coming from both local and lower brainstem neurons converge on a single LG soma. Excitatory neurons in IC can innervate many nearby LG somata in the same fibrodendritic lamina. The combination of local and ascending inputs is well suited for auditory integration. LG neurons are one of the main sources of inhibition in the medial geniculate body (MGB). LG neurons and the tectothalamic inhibitory system are present in a wide variety of mammalian species. This suggests that the circuitry of excitatory and inhibitory tectothalamic projections may have evolved earlier than GABAergic interneurons in the MGB, which are found in fewer species. Cellular-level functional imaging provides both morphological and functional information about local circuitry. In the last part of this review, we describe an in vivo calcium imaging study that sheds light on the functional organization of the IC.
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Affiliation(s)
- Tetsufumi Ito
- Department of Anatomy, Faculty of Medical Sciences, University of Fukui, Eiheiji, Fukui, 910-1193, Japan. .,Research and Education Program for Life Science, University of Fukui, Fukui, Fukui, 910-8507, Japan.
| | - Deborah C Bishop
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030-3401, USA
| | - Douglas L Oliver
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, 06030-3401, USA
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