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Holt AG, Griffith RD, Lee SD, Asako M, Buras E, Yalcinoglu S, Altschuler RA. Ototoxicity-related changes in GABA immunolabeling within the rat inferior colliculus. Hear Res 2024; 452:109106. [PMID: 39181061 DOI: 10.1016/j.heares.2024.109106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 07/29/2024] [Accepted: 08/15/2024] [Indexed: 08/27/2024]
Abstract
Several studies suggest that hearing loss results in changes in the balance between inhibition and excitation in the inferior colliculus (IC). The IC is an integral nucleus within the auditory brainstem. The majority of ascending pathways from the lateral lemniscus (LL), superior olivary complex (SOC), and cochlear nucleus (CN) synapse in the IC before projecting to the thalamus and cortex. Many of these ascending projections provide inhibitory innervation to neurons within the IC. However, the nature and the distribution of this inhibitory input have only been partially elucidated in the rat. The inhibitory neurotransmitter, gamma aminobutyric acid (GABA), from the ventral nucleus of the lateral lemniscus (VNLL), provides the primary inhibitory input to the IC of the rat with GABA from other lemniscal and SOC nuclei providing lesser, but prominent innervation. There is evidence that hearing related conditions can result in dysfunction of IC neurons. These changes may be mediated in part by changes in GABA inputs to IC neurons. We have previously used gene micro-arrays in a study of deafness-related changes in gene expression in the IC and found significant changes in GAD as well as the GABA transporters and GABA receptors (Holt 2005). This is consistent with reports of age and trauma related changes in GABA (Bledsoe et al., 1995; Mossop et al., 2000; Salvi et al., 2000). Ototoxic lesions of the cochlea produced a permanent threshold shift. The number, intensity, and density of GABA positive axon terminals in the IC were compared in normal hearing and deafened rats. While the number of GABA immunolabeled puncta was only minimally different between groups, the intensity of labeling was significantly reduced. The ultrastructural localization and distribution of labeling was also examined. In deafened animals, the number of immuno gold particles was reduced by 78 % in axodendritic and 82 % in axosomatic GABAergic puncta. The affected puncta were primarily associated with small IC neurons. These results suggest that reduced inhibition to IC neurons contribute to the increased neuronal excitability observed in the IC following noise or drug induced hearing loss. Whether these deafness diminished inhibitory inputs originate from intrinsic or extrinsic CNIC sources awaits further study.
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Affiliation(s)
- Avril Genene Holt
- Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48201, United States of America.
| | - Ronald D Griffith
- Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48201, United States of America
| | - Soo D Lee
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Mikiya Asako
- Department of Otolaryngology, Kansai Medical University, Takii Hospital, 10-15 Fumizono-cho, Moriguchi, Osaka 570-8506, Japan
| | - Eric Buras
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Selin Yalcinoglu
- Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48201, United States of America
| | - Richard A Altschuler
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, United States of America; Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, United States of America
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Parameshwarappa V, Siponen MI, Watabe I, Karkaba A, Galazyuk A, Noreña AJ. Noise-induced hearing loss alters potassium-chloride cotransporter KCC2 and GABA inhibition in the auditory centers. Sci Rep 2024; 14:10689. [PMID: 38724641 PMCID: PMC11082187 DOI: 10.1038/s41598-024-60858-1] [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: 09/26/2023] [Accepted: 04/29/2024] [Indexed: 05/12/2024] Open
Abstract
Homeostatic plasticity, the ability of neurons to maintain their averaged activity constant around a set point value, is thought to account for the central hyperactivity after hearing loss. Here, we investigated the putative role of GABAergic neurotransmission in this mechanism after a noise-induced hearing loss larger than 50 dB in high frequencies in guinea pigs. The effect of GABAergic inhibition is linked to the normal functioning of K + -Cl- co-transporter isoform 2 (KCC2) which maintains a low intracellular concentration of chloride. The expression of membrane KCC2 were investigated before and after noise trauma in the ventral and dorsal cochlear nucleus (VCN and DCN, respectively) and in the inferior colliculus (IC). Moreover, the effect of gabazine (GBZ), a GABA antagonist, was also studied on the neural activity in IC. We show that KCC2 is downregulated in VCN, DCN and IC 3 days after noise trauma, and in DCN and IC 30 days after the trauma. As expected, GBZ application in the IC of control animals resulted in an increase of spontaneous and stimulus-evoked activity. In the noise exposed animals, on the other hand, GBZ application decreased the stimulus-evoked activity in IC neurons. The functional implications of these central changes are discussed.
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Affiliation(s)
- V Parameshwarappa
- Laboratory of Cognitive Neurosciences, Centre National de la Recherche Scientifique, Aix-Marseille University, 3 Place Victor Hugo, 13003, Marseille, France
| | - M I Siponen
- Laboratory of Cognitive Neurosciences, Centre National de la Recherche Scientifique, Aix-Marseille University, 3 Place Victor Hugo, 13003, Marseille, France
| | - I Watabe
- Laboratory of Cognitive Neurosciences, Centre National de la Recherche Scientifique, Aix-Marseille University, 3 Place Victor Hugo, 13003, Marseille, France
| | - A Karkaba
- Laboratory of Cognitive Neurosciences, Centre National de la Recherche Scientifique, Aix-Marseille University, 3 Place Victor Hugo, 13003, Marseille, France
| | - A Galazyuk
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, USA
| | - A J Noreña
- Laboratory of Cognitive Neurosciences, Centre National de la Recherche Scientifique, Aix-Marseille University, 3 Place Victor Hugo, 13003, Marseille, France.
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3
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Parameshwarappa V, Siponen M, Watabe I, Karkaba A, Galazyuk A, Noreña A. Noise-Induced Hearing Loss Alters Potassium-Chloride CoTransporter KCC2 and GABA Inhibition in the auditory centers. RESEARCH SQUARE 2023:rs.3.rs-3389804. [PMID: 37886592 PMCID: PMC10602088 DOI: 10.21203/rs.3.rs-3389804/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
Homeostatic plasticity, the ability of neurons to maintain their averaged activity constant around a set point value, is thought to account for the central hyperactivity after hearing loss. Here, we investigated the putative role of GABAergic neurotransmission in this mechanism after a noise-induced hearing loss larger than 50 dB in high frequencies in guinea pigs. The effect of GABAergic inhibition is linked to the normal functioning of K+-Cl- co-transporter isoform 2 (KCC2) which maintains a low intracellular concentration of chloride. The expression of membrane KCC2 were investigated before after noise trauma in the ventral and dorsal cochlear nucleus (VCN and DCN, respectively) and in the inferior colliculus (IC). Moreover, the effect of gabazine (GBZ), a GABA antagonist, was also studied on the neural activity in IC. We show that KCC2 is downregulated in VCN, DCN and IC 3 days after noise trauma, and in DCN and IC 30 days after the trauma. As expected, GBZ application in the IC of control animals resulted in an increase of spontaneous and stimulus-evoked activity. In the noise exposed animals, on the other hand, GBZ application decreased the stimulus-evoked activity in IC neurons. The functional implications of these central changes are discussed.
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Affiliation(s)
| | - Marina Siponen
- Centre National de la Recherche Scientifique, Aix- Marseille University
| | - Isabelle Watabe
- Centre National de la Recherche Scientifique, Aix- Marseille University
| | - Alaa Karkaba
- Centre National de la Recherche Scientifique, Aix- Marseille University
| | | | - Arnaud Noreña
- Centre National de la Recherche Scientifique, Aix- Marseille University
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Oberle HM, Ford AN, Czarny JE, Rogalla MM, Apostolides PF. Recurrent Circuits Amplify Corticofugal Signals and Drive Feedforward Inhibition in the Inferior Colliculus. J Neurosci 2023; 43:5642-5655. [PMID: 37308295 PMCID: PMC10401644 DOI: 10.1523/jneurosci.0626-23.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/02/2023] [Accepted: 06/06/2023] [Indexed: 06/14/2023] Open
Abstract
The inferior colliculus (IC) is a midbrain hub critical for perceiving complex sounds, such as speech. In addition to processing ascending inputs from most auditory brainstem nuclei, the IC receives descending inputs from auditory cortex that control IC neuron feature selectivity, plasticity, and certain forms of perceptual learning. Although corticofugal synapses primarily release the excitatory transmitter glutamate, many physiology studies show that auditory cortical activity has a net inhibitory effect on IC neuron spiking. Perplexingly, anatomy studies imply that corticofugal axons primarily target glutamatergic IC neurons while only sparsely innervating IC GABA neurons. Corticofugal inhibition of the IC may thus occur largely independently of feedforward activation of local GABA neurons. We shed light on this paradox using in vitro electrophysiology in acute IC slices from fluorescent reporter mice of either sex. Using optogenetic stimulation of corticofugal axons, we find that excitation evoked with single light flashes is indeed stronger in presumptive glutamatergic neurons compared with GABAergic neurons. However, many IC GABA neurons fire tonically at rest, such that sparse and weak excitation suffices to significantly increase their spike rates. Furthermore, a subset of glutamatergic IC neurons fire spikes during repetitive corticofugal activity, leading to polysynaptic excitation in IC GABA neurons owing to a dense intracollicular connectivity. Consequently, recurrent excitation amplifies corticofugal activity, drives spikes in IC GABA neurons, and generates substantial local inhibition in the IC. Thus, descending signals engage intracollicular inhibitory circuits despite apparent constraints of monosynaptic connectivity between auditory cortex and IC GABA neurons.SIGNIFICANCE STATEMENT Descending "corticofugal" projections are ubiquitous across mammalian sensory systems, and enable the neocortex to control subcortical activity in a predictive or feedback manner. Although corticofugal neurons are glutamatergic, neocortical activity often inhibits subcortical neuron spiking. How does an excitatory pathway generate inhibition? Here we study the corticofugal pathway from auditory cortex to inferior colliculus (IC), a midbrain hub important for complex sound perception. Surprisingly, cortico-collicular transmission was stronger onto IC glutamatergic compared with GABAergic neurons. However, corticofugal activity triggered spikes in IC glutamate neurons with local axons, thereby generating strong polysynaptic excitation and feedforward spiking of GABAergic neurons. Our results thus reveal a novel mechanism that recruits local inhibition despite limited monosynaptic convergence onto inhibitory networks.
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Affiliation(s)
- Hannah M Oberle
- Neuroscience Graduate Program
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
| | - Alexander N Ford
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
| | - Jordyn E Czarny
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
| | - Meike M Rogalla
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
| | - Pierre F Apostolides
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
- Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109
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Ibrahim BA, Louie JJ, Shinagawa Y, Xiao G, Asilador AR, Sable HJK, Schantz SL, Llano DA. Developmental Exposure to Polychlorinated Biphenyls Prevents Recovery from Noise-Induced Hearing Loss and Disrupts the Functional Organization of the Inferior Colliculus. J Neurosci 2023; 43:4580-4597. [PMID: 37147134 PMCID: PMC10286948 DOI: 10.1523/jneurosci.0030-23.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 03/20/2023] [Accepted: 04/17/2023] [Indexed: 05/07/2023] Open
Abstract
Exposure to combinations of environmental toxins is growing in prevalence; and therefore, understanding their interactions is of increasing societal importance. Here, we examined the mechanisms by which two environmental toxins, polychlorinated biphenyls (PCBs) and high-amplitude acoustic noise, interact to produce dysfunction in central auditory processing. PCBs are well established to impose negative developmental impacts on hearing. However, it is not known whether developmental exposure to this ototoxin alters the sensitivity to other ototoxic exposures later in life. Here, male mice were exposed to PCBs in utero, and later as adults were exposed to 45 min of high-intensity noise. We then examined the impacts of the two exposures on hearing and the organization of the auditory midbrain using two-photon imaging and analysis of the expression of mediators of oxidative stress. We observed that developmental exposure to PCBs blocked hearing recovery from acoustic trauma. In vivo two-photon imaging of the inferior colliculus (IC) revealed that this lack of recovery was associated with disruption of the tonotopic organization and reduction of inhibition in the auditory midbrain. In addition, expression analysis in the inferior colliculus revealed that reduced GABAergic inhibition was more prominent in animals with a lower capacity to mitigate oxidative stress. These data suggest that combined PCBs and noise exposure act nonlinearly to damage hearing and that this damage is associated with synaptic reorganization, and reduced capacity to limit oxidative stress. In addition, this work provides a new paradigm by which to understand nonlinear interactions between combinations of environmental toxins.SIGNIFICANCE STATEMENT Exposure to common environmental toxins is a large and growing problem in the population. This work provides a new mechanistic understanding of how the prenatal and postnatal developmental changes induced by polychlorinated biphenyls (PCBs) could negatively impact the resilience of the brain to noise-induced hearing loss (NIHL) later in adulthood. The use of state-of-the-art tools, including in vivo multiphoton microscopy of the midbrain helped in identifying the long-term central changes in the auditory system after the peripheral hearing damage induced by such environmental toxins. In addition, the novel combination of methods employed in this study will lead to additional advances in our understanding of mechanisms of central hearing loss in other contexts.
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Affiliation(s)
- Baher A Ibrahim
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Jeremy J Louie
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Yoshitaka Shinagawa
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Gang Xiao
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Alexander R Asilador
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Helen J K Sable
- The Department of Psychology, The University of Memphis, Memphis, Tennessee 38152
| | - Susan L Schantz
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Department of Comparative Biosciences, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Daniel A Llano
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Carle Illinois College of Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
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Koehler CC, Almassri LS, Tokar N, Mafi AM, O’Hara MJ, Young JW, Mellott JG. Age-related Changes of GAD1 mRNA Expression in the Central Inferior Colliculus. TRANSLATIONAL MEDICINE OF AGING 2023; 7:20-32. [PMID: 38111912 PMCID: PMC10727507 DOI: 10.1016/j.tma.2023.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023] Open
Abstract
Encoding sounds with a high degree of temporal precision is an essential task for the inferior colliculus (IC) to perform and maintain the accurate processing of sounds and speech. However, the age-related reduction of GABAergic neurotransmission in the IC interrupts temporal precision and likely contributes to presbycusis. As presbycusis often manifests at high or low frequencies specifically, we sought to determine if the expression of mRNA for glutamic decarboxylase 1 (GAD1) is downregulated non-uniformly across the tonotopic axis or cell size range in the aging IC. Using single molecule in situ fluorescent hybridization across young, middle age and old Fisher Brown Norway rats (an aging model that acquires low frequency presbycusis) we quantified individual GAD1 mRNA in small, medium and large GABAergic cells. Our results demonstrate that small GABAergic cells in low frequency regions had ~58% less GAD1 in middle age and continued to decline into old age. In contrast, the amount of GAD1 mRNA in large cells in low frequency regions significantly increased with age. As several studies have shown that downregulation of GAD1 decreases the release of GABA, we interpret our results in two ways. First, the onset of presbycusis may be driven by small GABAergic cells downregulating GAD1. Second, as previous studies demonstrate that GAD67 expression is broadly downregulated in the old IC, perhaps the translation of GAD1 to GAD67 is interrupted in large GABAergic IC cells during aging. These results point to a potential genetic mechanism explaining reduced temporal precision in the aging IC, and in turn, presbycusis.
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Affiliation(s)
- Christina C. Koehler
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Laila S. Almassri
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Nick Tokar
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Amir M. Mafi
- The Ohio State College of Medicine The Ohio State Columbus, OH USA
| | - Mitchell J. O’Hara
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Jesse W. Young
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Jeffrey G. Mellott
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
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de Oliveira RP, Yokoyama T, Cardoso Thomaz LDS, de Andrade JS, Santos ADA, de Carvalho Mendonça V, Rosentock T, Carrera M, Medeiros P, Cruz FC, Coimbra NC, Silva RCB. Prepulse inhibition of the acoustic startle reflex impairment by 5-HT2A receptor activation in the inferior colliculusis prevented by GABAA receptor blockade in the pedunculopontine tegmental nucleus. Behav Brain Res 2023; 448:114436. [PMID: 37061200 DOI: 10.1016/j.bbr.2023.114436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 04/10/2023] [Accepted: 04/10/2023] [Indexed: 04/17/2023]
Abstract
The relationship between serotonin dysfunction and schizophrenia commenced with the discovery of the effects of lysergic acid diethylamide (LSD) that has high affinity for 5-HT2A receptors. Activation of these receptors produces perceptual and behavioural changes such as illusions, visual hallucinations and locomotor hyperactivity. Using prepulse inhibition (PPI) of the acoustic startle, which is impaired in schizophrenia,we aimed to investigate:i) the existence of a direct and potentially inhibitory neural pathway between the inferior colliculus (IC) and the pedunculopontine tegmental nucleus (PPTg) involved in the mediation of PPI responses by a neural tract tracing procedure;ii) if the microinjection of the 5-HT2A receptors agonist DOI in IC would activate neurons in this structure and in the PPTg by a c-Fos protein immunohistochemistry study;iii) whether the deficits in PPI responses, observed after the administration of DOI in the IC, could be prevented by the concomitant microinjection of the GABAA receptor antagonist bicuculline in the PPTg.Male Wistar rats were used in this study. An IC-PPTg reciprocated neuronal pathway was identified by neurotracing. The number of c-Fos labelled cells was lower in the DOI group in IC and PPTg, suggesting that this decrease could be due to the high levels of GABA in both structures. The concomitant microinjections of bicuculline in PPTg and DOI in IC prevented the PPI deficit observed after the IC microinjection of DOI. Ourfindings suggest that IC 5-HT2A receptors may be at least partially involved in the regulation of inhibitory pathways mediating PPI response in IC and PPTg structures.
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Affiliation(s)
- Rodolpho Pereira de Oliveira
- Laboratory of Psychobiology of Schizophrenia, Departmentof Biosciences, Federal University of São Paulo (UNIFESP), Silva Jardim Street 136, Santos, 11015-020, São Paulo, Brazil
| | - Thais Yokoyama
- Department of Pharmacology, - Federal University of São Paulo (UNIFESP), São Paulo-SP, 04023-062, Brazil
| | - Lucas de Santana Cardoso Thomaz
- Laboratory of Psychobiology of Schizophrenia, Departmentof Biosciences, Federal University of São Paulo (UNIFESP), Silva Jardim Street 136, Santos, 11015-020, São Paulo, Brazil
| | - José Simões de Andrade
- Laboratory of Psychobiology of Schizophrenia, Departmentof Biosciences, Federal University of São Paulo (UNIFESP), Silva Jardim Street 136, Santos, 11015-020, São Paulo, Brazil
| | - Alexia Dos Anjos Santos
- Department of Pharmacology, - Federal University of São Paulo (UNIFESP), São Paulo-SP, 04023-062, Brazil
| | - Vinícius de Carvalho Mendonça
- Laboratory of Psychobiology of Schizophrenia, Departmentof Biosciences, Federal University of São Paulo (UNIFESP), Silva Jardim Street 136, Santos, 11015-020, São Paulo, Brazil
| | - Tatiana Rosentock
- Sygnature Discovery, Department of Bioscience, BioCity, Pennyfoot Street, Nottingham, NG1 1GR, United Kingdom
| | - Marinete Carrera
- Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602, RJ, Brazil
| | - Priscila Medeiros
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, RibeirãoPreto Medical School of the Univertsity of São Paulo (FMRP-USP), Av. Bandeirantes, 30900, RibeirãoPreto, 14049-900, São Paulo, Brazil; Laboratory of Neurosciences of Pain & Emotion, Department of Surgery and Anatomy, FMRP-USP, Av. Bandeirantes, 3900, Ribeirão Preto, 14049-900, São Paulo, Brazil; InstituteofNeuroscienceandBehavior (INeC), Av. do Café, 2450, Monte Alegre, Ribeirão Preto, 14050-220, São Paulo, Brazil; Interdisciplinary Center for PainCare, Federal Universityof São Carlos (UFSCar), Universidade Federal de São Carlos, Rodovia Washington Luiz, Km 235, Caixa Postal 676, CEP 13565-905, SP, Brazil; Department of General and Specialized Nursing - EERP/USP RibeirãoPreto College of Nursing - USP
| | - Fábio Cardoso Cruz
- Department of Pharmacology, - Federal University of São Paulo (UNIFESP), São Paulo-SP, 04023-062, Brazil
| | - Norberto Cysne Coimbra
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, RibeirãoPreto Medical School of the Univertsity of São Paulo (FMRP-USP), Av. Bandeirantes, 30900, RibeirãoPreto, 14049-900, São Paulo, Brazil; Laboratory of Neurosciences of Pain & Emotion, Department of Surgery and Anatomy, FMRP-USP, Av. Bandeirantes, 3900, Ribeirão Preto, 14049-900, São Paulo, Brazil; InstituteofNeuroscienceandBehavior (INeC), Av. do Café, 2450, Monte Alegre, Ribeirão Preto, 14050-220, São Paulo, Brazil
| | - Regina Cláudia Barbosa Silva
- Laboratory of Psychobiology of Schizophrenia, Departmentof Biosciences, Federal University of São Paulo (UNIFESP), Silva Jardim Street 136, Santos, 11015-020, São Paulo, Brazil; InstituteofNeuroscienceandBehavior (INeC), Av. do Café, 2450, Monte Alegre, Ribeirão Preto, 14050-220, São Paulo, Brazil.
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8
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Ibrahim BA, Louie J, Shinagawa Y, Xiao G, Asilador AR, Sable HJK, Schantz SL, Llano DA. Developmental exposure to polychlorinated biphenyls prevents recovery from noise-induced hearing loss and disrupts the functional organization of the inferior colliculus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.23.534008. [PMID: 36993666 PMCID: PMC10055398 DOI: 10.1101/2023.03.23.534008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Exposure to combinations of environmental toxins is growing in prevalence, and therefore understanding their interactions is of increasing societal importance. Here, we examined the mechanisms by which two environmental toxins - polychlorinated biphenyls (PCBs) and high-amplitude acoustic noise - interact to produce dysfunction in central auditory processing. PCBs are well-established to impose negative developmental impacts on hearing. However, it is not known if developmental exposure to this ototoxin alters the sensitivity to other ototoxic exposures later in life. Here, male mice were exposed to PCBs in utero, and later as adults were exposed to 45 minutes of high-intensity noise. We then examined the impacts of the two exposures on hearing and the organization of the auditory midbrain using two-photon imaging and analysis of the expression of mediators of oxidative stress. We observed that developmental exposure to PCBs blocked hearing recovery from acoustic trauma. In vivo two-photon imaging of the inferior colliculus revealed that this lack of recovery was associated with disruption of the tonotopic organization and reduction of inhibition in the auditory midbrain. In addition, expression analysis in the inferior colliculus revealed that reduced GABAergic inhibition was more prominent in animals with a lower capacity to mitigate oxidative stress. These data suggest that combined PCBs and noise exposure act nonlinearly to damage hearing and that this damage is associated with synaptic reorganization, and reduced capacity to limit oxidative stress. In addition, this work provides a new paradigm by which to understand nonlinear interactions between combinations of environmental toxins. Significance statement Exposure to common environmental toxins is a large and growing problem in the population. This work provides a new mechanistic understanding of how the pre-and postnatal developmental changes induced by polychlorinated biphenyls could negatively impact the resilience of the brain to noise-induced hearing loss later in adulthood. The use of state-of-the-art tools, including in vivo multiphoton microscopy of the midbrain helped in identifying the long-term central changes in the auditory system after the peripheral hearing damage induced by such environmental toxins. In addition, the novel combination of methods employed in this study will lead to additional advances in our understanding of mechanisms of central hearing loss in other contexts.
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Affiliation(s)
- Baher A. Ibrahim
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Jeremy Louie
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Yoshitaka Shinagawa
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Gang Xiao
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Alexander R. Asilador
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Helen J. K. Sable
- The Department of Psychology, The University of Memphis, Memphis, TN 38152, USA
| | - Susan L. Schantz
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Department of Comparative Biosciences, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Daniel A. Llano
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Carle Illinois College of Medicine, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
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9
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Burghard AL, Lee CM, Fabrizio-Stover EM, Oliver DL. Long-Duration Sound-Induced Facilitation Changes Population Activity in the Inferior Colliculus. Front Syst Neurosci 2022; 16:920642. [PMID: 35873097 PMCID: PMC9301083 DOI: 10.3389/fnsys.2022.920642] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/03/2022] [Indexed: 11/13/2022] Open
Abstract
The inferior colliculus (IC) is at the midpoint of the auditory system and integrates virtually all information ascending from the auditory brainstem, organizes it, and transmits the results to the auditory forebrain. Its abundant, excitatory local connections are crucial for this task. This study describes a long duration sound (LDS)-induced potentiation in the IC that changes both subsequent tone-evoked responses and spontaneous activity. Afterdischarges, changes of spontaneous spiking following an LDS, were seen previously in single neurons. Here, we used multi-channel probes to record activity before and after a single, tetanic sound and describe the changes in a population of IC neurons. Following a 60 s narrowband-noise stimulation, a subset of recording channels (∼16%) showed afterdischarges. A facilitated response spike rate to tone pips following an LDS was also observed in ∼16% of channels. Both channels with an afterdischarge and channels with facilitated tone responses had higher firing rates in response to LDS, and the magnitude of the afterdischarges increased with increased responses to the LDS. This is the first study examining the effect of LDS stimulation on tone-evoked responses. This observed facilitation in vivo has similarities to post-tetanic potentiation in vitro as both manner of induction (strong stimulation for several seconds) as well as time-course of the facilitation (second to minute range) are comparable. Channels with and without facilitation appear to be intermixed and distributed widely in the central nucleus of IC, and this suggests a heretofore unknown property of some IC neurons or their circuits. Consequently, this sound-evoked facilitation may enhance the sound-evoked output of these neurons, while, simultaneously, most other IC neurons have reduced or unchanged output in response to the same stimulus.
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10
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The role of the medial geniculate body of the thalamus in the pathophysiology of tinnitus and implications for treatment. Brain Res 2022; 1779:147797. [DOI: 10.1016/j.brainres.2022.147797] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 11/25/2021] [Accepted: 01/13/2022] [Indexed: 01/12/2023]
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11
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Beebe NL, Schofield BR. Cholinergic boutons are closely associated with excitatory cells and four subtypes of inhibitory cells in the inferior colliculus. J Chem Neuroanat 2021; 116:101998. [PMID: 34186203 DOI: 10.1016/j.jchemneu.2021.101998] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/23/2021] [Accepted: 06/24/2021] [Indexed: 01/23/2023]
Abstract
Acetylcholine (ACh) is a neuromodulator that has been implicated in multiple roles across the brain, including the central auditory system, where it sets neuronal excitability and gain and affects plasticity. In the cerebral cortex, subtypes of GABAergic interneurons are modulated by ACh in a subtype-specific manner. Subtypes of GABAergic neurons have also begun to be described in the inferior colliculus (IC), a midbrain hub of the auditory system. Here, we used male and female mice (Mus musculus) that express fluorescent protein in cholinergic cells, axons, and boutons to look at the association between ACh and four subtypes of GABAergic IC cells that differ in their associations with extracellular markers, their soma sizes, and their distribution within the IC. We found that most IC cells, including excitatory and inhibitory cells, have cholinergic boutons closely associated with their somas and proximal dendrites. We also found that similar proportions of each of four subtypes of GABAergic cells are closely associated with cholinergic boutons. Whether the different types of GABAergic cells in the IC are differentially regulated remains unclear, as the response of cells to ACh is dependent on which types of ACh receptors are present. Additionally, this study confirms the presence of these four subtypes of GABAergic cells in the mouse IC, as they had previously been identified only in guinea pigs. These results suggest that cholinergic projections to the IC modulate auditory processing via direct effects on a multitude of inhibitory circuits.
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Affiliation(s)
- Nichole L Beebe
- Hearing Research Focus Group, Northeast Ohio Medical University, Rootstown, OH, USA; Brain Health Research Institute, Kent State University, Kent, OH, USA.
| | - Brett R Schofield
- Hearing Research Focus Group, Northeast Ohio Medical University, Rootstown, OH, USA; Brain Health Research Institute, Kent State University, Kent, OH, USA.
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12
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Bordia T, Zahr NM. The Inferior Colliculus in Alcoholism and Beyond. Front Syst Neurosci 2020; 14:606345. [PMID: 33362482 PMCID: PMC7759542 DOI: 10.3389/fnsys.2020.606345] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 11/02/2020] [Indexed: 12/28/2022] Open
Abstract
Post-mortem neuropathological and in vivo neuroimaging methods have demonstrated the vulnerability of the inferior colliculus to the sequelae of thiamine deficiency as occurs in Wernicke-Korsakoff Syndrome (WKS). A rich literature in animal models ranging from mice to monkeys-including our neuroimaging studies in rats-has shown involvement of the inferior colliculi in the neural response to thiamine depletion, frequently accomplished with pyrithiamine, an inhibitor of thiamine metabolism. In uncomplicated alcoholism (i.e., absent diagnosable neurological concomitants), the literature citing involvement of the inferior colliculus is scarce, has nearly all been accomplished in preclinical models, and is predominately discussed in the context of ethanol withdrawal. Our recent work using novel, voxel-based analysis of structural Magnetic Resonance Imaging (MRI) has demonstrated significant, persistent shrinkage of the inferior colliculus using acute and chronic ethanol exposure paradigms in two strains of rats. We speculate that these consistent findings should be considered from the perspective of the inferior colliculi having a relatively high CNS metabolic rate. As such, they are especially vulnerable to hypoxic injury and may be provide a common anatomical link among a variety of disparate insults. An argument will be made that the inferior colliculi have functions, possibly related to auditory gating, necessary for awareness of the external environment. Multimodal imaging including diffusion methods to provide more accurate in vivo visualization and quantification of the inferior colliculi may clarify the roles of brain stem nuclei such as the inferior colliculi in alcoholism and other neuropathologies marked by altered metabolism.
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Affiliation(s)
- Tanuja Bordia
- Neuroscience Program, SRI International, Menlo Park, CA, United States
| | - Natalie M. Zahr
- Neuroscience Program, SRI International, Menlo Park, CA, United States
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, United States
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13
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Neuropeptide Y Expression Defines a Novel Class of GABAergic Projection Neuron in the Inferior Colliculus. J Neurosci 2020; 40:4685-4699. [PMID: 32376782 DOI: 10.1523/jneurosci.0420-20.2020] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 04/22/2020] [Accepted: 05/01/2020] [Indexed: 12/24/2022] Open
Abstract
Located in the midbrain, the inferior colliculus (IC) integrates information from numerous auditory nuclei and is an important hub for sound processing. Despite its importance, little is known about the molecular identity and functional roles of defined neuron types in the IC. Using a multifaceted approach in mice of both sexes, we found that neuropeptide Y (NPY) expression identifies a major class of inhibitory neurons, accounting for approximately one-third of GABAergic neurons in the IC. Retrograde tracing showed that NPY neurons are principal neurons that can project to the medial geniculate nucleus. In brain slice recordings, many NPY neurons fired spontaneously, suggesting that NPY neurons may drive tonic inhibition onto postsynaptic targets. Morphologic reconstructions showed that NPY neurons are stellate cells, and the dendrites of NPY neurons in the tonotopically organized central nucleus of the IC cross isofrequency laminae. Immunostaining confirmed that NPY neurons express NPY, and we therefore hypothesized that NPY signaling regulates activity in the IC. In crosses between Npy1rcre and Ai14 Cre-reporter mice, we found that NPY Y1 receptor (Y1R)-expressing neurons are glutamatergic and were broadly distributed throughout the rostrocaudal extent of the IC. In whole-cell recordings, application of a high-affinity Y1R agonist led to hyperpolarization in most Y1R-expressing IC neurons. Thus, NPY neurons represent a novel class of inhibitory principal neurons that are well poised to use GABAergic and NPY signaling to regulate the excitability of circuits in the IC and auditory thalamus.SIGNIFICANCE STATEMENT The identification of neuron types is a fundamental question in neuroscience. In the inferior colliculus (IC), the hub of the central auditory pathway, molecular markers for distinct classes of inhibitory neurons have remained unknown. We found that neuropeptide Y (NPY) expression identifies a class of GABAergic principal neurons that constitute one-third of the inhibitory neurons in the IC. NPY neurons fire spontaneously, have a stellate morphology, and project to the auditory thalamus. Additionally, we found that NPY signaling hyperpolarized the membrane potential of a subset of excitatory IC neurons that express the NPY Y1 receptor. Thus, NPY neurons are a novel class of inhibitory neurons that use GABA and NPY signaling to regulate activity in the IC and auditory thalamus.
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14
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Beebe NL, Noftz WA, Schofield BR. Perineuronal nets and subtypes of GABAergic cells differentiate auditory and multisensory nuclei in the intercollicular area of the midbrain. J Comp Neurol 2020; 528:2695-2707. [PMID: 32304096 DOI: 10.1002/cne.24926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 11/10/2022]
Abstract
The intercollicular region, which lies between the inferior and superior colliculi in the midbrain, contains neurons that respond to auditory, visual, and somatosensory stimuli. Golgi studies have been used to parse this region into three distinct nuclei: the intercollicular tegmentum (ICt), the rostral pole of the inferior colliculus (ICrp), and the nucleus of the brachium of the IC (NBIC). Few reports have focused on these nuclei, especially the ICt and the ICrp, possibly due to lack of a marker that distinguishes these areas and is compatible with modern methods. Here, we found that staining for GABAergic cells and perineuronal nets differentiates these intercollicular nuclei in guinea pigs. Further, we found that the proportions of four subtypes of GABAergic cells differentiate intercollicular nuclei from each other and from adjacent inferior collicular subdivisions. Our results support earlier studies that suggest distinct morphology and functions for intercollicular nuclei, and provide staining methods that differentiate intercollicular nuclei and are compatible with most modern techniques. We hope that this will help future studies to further characterize the intercollicular region.
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Affiliation(s)
- Nichole L Beebe
- Hearing Research Group, Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - William A Noftz
- Hearing Research Group, Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, USA.,Biomedical Sciences Program, Kent State University, Kent, Ohio, USA
| | - Brett R Schofield
- Hearing Research Group, Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, USA.,Biomedical Sciences Program, Kent State University, Kent, Ohio, USA
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15
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Yang Y, Lee J, Kim G. Integration of locomotion and auditory signals in the mouse inferior colliculus. eLife 2020; 9:52228. [PMID: 31987070 PMCID: PMC7004561 DOI: 10.7554/elife.52228] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 01/16/2020] [Indexed: 01/10/2023] Open
Abstract
The inferior colliculus (IC) is the major midbrain auditory integration center, where virtually all ascending auditory inputs converge. Although the IC has been extensively studied for sound processing, little is known about the neural activity of the IC in moving subjects, as frequently happens in natural hearing conditions. Here, by recording neural activity in walking mice, we show that the activity of IC neurons is strongly modulated by locomotion, even in the absence of sound stimuli. Similar modulation was also found in hearing-impaired mice, demonstrating that IC neurons receive non-auditory, locomotion-related neural signals. Sound-evoked activity was attenuated during locomotion, and this attenuation increased frequency selectivity across the neuronal population, while maintaining preferred frequencies. Our results suggest that during behavior, integrating movement-related and auditory information is an essential aspect of sound processing in the IC.
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Affiliation(s)
- Yoonsun Yang
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea.,Department of Physiology, School of Medicine, Sungkyunkwan University, Suwon, Republic of Korea
| | - Joonyeol Lee
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
| | - Gunsoo Kim
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea.,Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
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16
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Vila CH, Williamson RS, Hancock KE, Polley DB. Optimizing optogenetic stimulation protocols in auditory corticofugal neurons based on closed-loop spike feedback. J Neural Eng 2019; 16:066023. [PMID: 31394519 PMCID: PMC6956656 DOI: 10.1088/1741-2552/ab39cf] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Optogenetics provides a means to probe functional connections between brain areas. By activating a set of presynaptic neurons and recording the activity from a downstream brain area, one can establish the sign and strength of a feedforward connection. One challenge is that there are virtually limitless patterns that can be used to stimulate a presynaptic brain area. Functional influences on downstream brain areas can depend not just on whether presynaptic neurons were activated, but how they were activated. Corticofugal axons from the auditory cortex (ACtx) heavily innervate the auditory tectum, the inferior colliculus (IC). Here, we sought to determine whether different modes of corticocollicular activation could titrate the strength of feedforward modulation of sound processing in IC neurons. APPROACH We used multi-channel electrophysiology and optogenetics to record from multiple regions of the IC in awake head-fixed mice while optogenetically stimulating ACtx neurons expressing Chronos, an ultra-fast channelrhodopsin. To identify cortical activation patterns associated with the strongest effects on IC firing rates, we employed a closed-loop evolutionary optimization procedure that tailored the voltage command signal sent to the laser based on spike feedback from single IC neurons. MAIN RESULTS Within minutes, our evolutionary search procedure converged on ACtx stimulation configurations that produced more effective and widespread enhancement of IC unit activity than generic activation parameters. Cortical modulation of midbrain spiking was bi-directional, as the evolutionary search procedure could be programmed to converge on activation patterns that either suppressed or enhanced sound-evoked IC firing rate. SIGNIFICANCE This study introduces a closed-loop optimization procedure to probe functional connections between brain areas. Our findings demonstrate that the influence of descending feedback projections on subcortical sensory processing can vary both in sign and degree depending on how cortical neurons are activated in time.
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Affiliation(s)
- Charles-Henri Vila
- - Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston MA 02114 USA
- - Bertarelli Fellows Program, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Ross S Williamson
- - Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston MA 02114 USA
- - Dept. Otolaryngology, Harvard Medical School, Boston MA 02114
| | - Kenneth E Hancock
- - Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston MA 02114 USA
- - Dept. Otolaryngology, Harvard Medical School, Boston MA 02114
| | - Daniel B Polley
- - Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston MA 02114 USA
- - Dept. Otolaryngology, Harvard Medical School, Boston MA 02114
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17
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Wong AB, Borst JGG. Tonotopic and non-auditory organization of the mouse dorsal inferior colliculus revealed by two-photon imaging. eLife 2019; 8:49091. [PMID: 31612853 PMCID: PMC6834370 DOI: 10.7554/elife.49091] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/13/2019] [Indexed: 12/17/2022] Open
Abstract
The dorsal (DCIC) and lateral cortices (LCIC) of the inferior colliculus are major targets of the auditory and non-auditory cortical areas, suggesting a role in complex multimodal information processing. However, relatively little is known about their functional organization. We utilized in vivo two-photon Ca2+ imaging in awake mice expressing GCaMP6s in GABAergic or non-GABAergic neurons in the IC to investigate their spatial organization. We found different classes of temporal responses, which we confirmed with simultaneous juxtacellular electrophysiology. Both GABAergic and non-GABAergic neurons showed spatial microheterogeneity in their temporal responses. In contrast, a robust, double rostromedial-caudolateral gradient of frequency tuning was conserved between the two groups, and even among the subclasses. This, together with the existence of a subset of neurons sensitive to spontaneous movements, provides functional evidence for redefining the border between DCIC and LCIC.
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Affiliation(s)
- Aaron Benson Wong
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - J Gerard G Borst
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
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18
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Liu Y, Zhang G, Yu H, Li H, Wei J, Xiao Z. Robust and Intensity-Dependent Synaptic Inhibition Underlies the Generation of Non-monotonic Neurons in the Mouse Inferior Colliculus. Front Cell Neurosci 2019; 13:131. [PMID: 31024260 PMCID: PMC6460966 DOI: 10.3389/fncel.2019.00131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 03/15/2019] [Indexed: 11/28/2022] Open
Abstract
Intensity and frequency are the two main properties of sound. The non-monotonic neurons in the auditory system are thought to represent sound intensity. The central nucleus of the inferior colliculus (ICC), as an important information integration nucleus of the auditory system, is also involved in the processing of intensity encoding. Although previous researchers have hinted at the importance of inhibitory effects on the formation of non-monotonic neurons, the specific underlying synaptic mechanisms in the ICC are still unclear. Therefore, we applied the in vivo whole-cell voltage-clamp technique to record the excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) in the ICC neurons, and compared the effects of excitation and inhibition on the membrane potential outputs. We found that non-monotonic neuron responses could not only be inherited from the lower nucleus but also be created in the ICC. By integrating with a relatively weak IPSC, approximately 35% of the monotonic excitatory inputs remained in the ICC. In the remaining cases, monotonic excitatory inputs were reshaped into non-monotonic outputs by the dominating inhibition at high intensity, which also enhanced the non-monotonic nature of the non-monotonic excitatory inputs.
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Affiliation(s)
- Yun Liu
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Guangzhou, China
| | - Guodong Zhang
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Guangzhou, China
| | - Haipeng Yu
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Guangzhou, China
| | - He Li
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Guangzhou, China
| | - Jinxing Wei
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Guangzhou, China
| | - Zhongju Xiao
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Key Laboratory of Psychiatric Disorders of Guangdong Province, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Mental Health of the Ministry of Education, Guangzhou, China
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19
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Goyer D, Silveira MA, George AP, Beebe NL, Edelbrock RM, Malinski PT, Schofield BR, Roberts MT. A novel class of inferior colliculus principal neurons labeled in vasoactive intestinal peptide-Cre mice. eLife 2019; 8:43770. [PMID: 30998185 PMCID: PMC6516826 DOI: 10.7554/elife.43770] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 04/17/2019] [Indexed: 12/17/2022] Open
Abstract
Located in the midbrain, the inferior colliculus (IC) is the hub of the central auditory system. Although the IC plays important roles in speech processing, sound localization, and other auditory computations, the organization of the IC microcircuitry remains largely unknown. Using a multifaceted approach in mice, we have identified vasoactive intestinal peptide (VIP) neurons as a novel class of IC principal neurons. VIP neurons are glutamatergic stellate cells with sustained firing patterns. Their extensive axons project to long-range targets including the auditory thalamus, auditory brainstem, superior colliculus, and periaqueductal gray. Using optogenetic circuit mapping, we found that VIP neurons integrate input from the contralateral IC and the dorsal cochlear nucleus. The dorsal cochlear nucleus also drove feedforward inhibition to VIP neurons, indicating that inhibitory circuits within the IC shape the temporal integration of ascending inputs. Thus, VIP neurons are well-positioned to influence auditory computations in a number of brain regions.
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Affiliation(s)
- David Goyer
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, United States
| | - Marina A Silveira
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, United States
| | - Alexander P George
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, United States
| | - Nichole L Beebe
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, United States
| | - Ryan M Edelbrock
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, United States
| | - Peter T Malinski
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, United States
| | - Brett R Schofield
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, United States
| | - Michael T Roberts
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, United States
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20
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Inhibitory Projections from the Inferior Colliculus to the Medial Geniculate body Originate from Four Subtypes of GABAergic Cells. eNeuro 2018; 5:eN-NWR-0406-18. [PMID: 30456294 PMCID: PMC6240760 DOI: 10.1523/eneuro.0406-18.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 10/25/2018] [Indexed: 12/26/2022] Open
Abstract
GABAergic cells constitute 20-40% of the cells that project from the inferior colliculus [(IC) a midbrain auditory hub] to the medial geniculate body [(MG) the main auditory nucleus of the thalamus]. Four subtypes of GABAergic IC cells have been identified based on their association with perineuronal nets (PNs) and dense rings of axosomatic terminals expressing vesicular glutamate transporter 2 (VGLUT2 rings). These subtypes differ in their soma size and distribution within the IC. Based on previous work emphasizing large GABAergic cells as the origin of GABAergic IC-MG projections, we hypothesized that GABAergic IC cells surrounded by PNs and VGLUT2 rings, which tend to have larger somas, were more likely to project to the MG than smaller cells lacking these extracellular markers. Here, we injected retrograde tract tracers into the MG of guinea pigs of either sex and analyzed retrogradely labeled GABAergic cells in the ipsilateral IC for soma size and association with PNs and/or VGLUT2 rings. We found a range of GABAergic soma sizes present within the IC-MG pathway, which were reflective of the full range of GABAergic soma sizes present within the IC. Further, we found that all four subtypes of GABAergic IC cells participate in the IC-MG pathway, and that GABAergic cells lacking PNs and VGLUT2 rings were more prevalent within the pathway than would be expected based on their overall prevalence in the IC. These results may provide an anatomical substrate for the multiple roles of inhibition in the IC-MG pathway, which have emerged in electrophysiological studies.
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