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Huson V, Newman L, Regehr WG. A Continuum of Response Properties across the Population of Unipolar Brush Cells in the Dorsal Cochlear Nucleus. J Neurosci 2023; 43:6035-6045. [PMID: 37507229 PMCID: PMC10451148 DOI: 10.1523/jneurosci.0873-23.2023] [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: 05/11/2023] [Revised: 07/14/2023] [Accepted: 07/24/2023] [Indexed: 07/30/2023] Open
Abstract
Unipolar brush cells (UBCs) in the cerebellum and dorsal cochlear nucleus (DCN) perform temporal transformations by converting brief mossy fiber bursts into long-lasting responses. In the cerebellar UBC population, mixing inhibition with graded mGluR1-dependent excitation leads to a continuum of temporal responses. In the DCN, it has been thought that mGluR1 contributes little to mossy fiber responses and that there are distinct excitatory and inhibitory UBC subtypes. Here, we investigate UBC response properties using noninvasive cell-attached recordings in the DCN of mice of either sex. We find a continuum of responses to mossy fiber bursts ranging from 100 ms excitation to initial inhibition followed by several seconds of excitation to inhibition lasting for hundreds of milliseconds. Pharmacological interrogation reveals excitatory responses are primarily mediated by mGluR1 Thus, UBCs in both the DCN and cerebellum rely on mGluR1 and have a continuum of response durations. The continuum of responses in the DCN may allow more flexible and efficient temporal processing than can be achieved with distinct excitatory and inhibitory populations.SIGNIFICANCE STATEMENT UBCs are specialized excitatory interneurons in cerebellar-like structures that greatly prolong the temporal responses of mossy fiber inputs. They are thought to help cancel out self-generated signals. In the DCN, the prevailing view was that there are two distinct ON and OFF subtypes of UBCs. Here, we show that instead the UBC population has a continuum of response properties. Many cells show suppression and excitation consecutively, and the response durations vary considerably. mGluR1s are crucial in generating a continuum of responses. To understand how UBCs contribute to temporal processing, it is essential to consider the continuous variations of UBC responses, which have advantages over just having opposing ON/OFF subtypes of UBCs.
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Affiliation(s)
- Vincent Huson
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Leannah Newman
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
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2
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Yamada R, Kuba H. Cellular Strategies for Frequency-Dependent Computation of Interaural Time Difference. Front Synaptic Neurosci 2022; 14:891740. [PMID: 35602551 PMCID: PMC9120351 DOI: 10.3389/fnsyn.2022.891740] [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: 03/08/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Binaural coincidence detection is the initial step in encoding interaural time differences (ITDs) for sound-source localization. In birds, neurons in the nucleus laminaris (NL) play a central role in this process. These neurons receive excitatory synaptic inputs on dendrites from both sides of the cochlear nucleus and compare their coincidences at the soma. The NL is tonotopically organized, and individual neurons receive a pattern of synaptic inputs that are specific to their tuning frequency. NL neurons differ in their dendritic morphology along the tonotopic axis; their length increases with lower tuning frequency. In addition, our series of studies have revealed several frequency-dependent refinements in the morphological and biophysical characteristics of NL neurons, such as the amount and subcellular distribution of ion channels and excitatory and inhibitory synapses, which enable the neurons to process the frequency-specific pattern of inputs appropriately and encode ITDs at each frequency band. In this review, we will summarize these refinements of NL neurons and their implications for the ITD coding. We will also discuss the similarities and differences between avian and mammalian coincidence detectors.
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3
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Mercuri NB, Federici M, Rizzo FR, Maugeri L, D'Addario SL, Ventura R, Berretta N. Long-Term Depression of Striatal DA Release Induced by mGluRs via Sustained Hyperactivity of Local Cholinergic Interneurons. Front Cell Neurosci 2021; 15:798464. [PMID: 34924961 PMCID: PMC8674918 DOI: 10.3389/fncel.2021.798464] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 11/15/2021] [Indexed: 12/21/2022] Open
Abstract
The cellular mechanisms regulating dopamine (DA) release in the striatum have attracted much interest in recent years. By in vitro amperometric recordings in mouse striatal slices, we show that a brief (5 min) exposure to the metabotropic glutamate receptor agonist DHPG (50 μM) induces a profound depression of synaptic DA release, lasting over 1 h from DHPG washout. This long-term depression is sensitive to glycine, which preferentially inhibits local cholinergic interneurons, as well as to drugs acting on nicotinic acetylcholine receptors and to the pharmacological depletion of released acetylcholine. The same DHPG treatment induces a parallel long-lasting enhancement in the tonic firing of presumed striatal cholinergic interneurons, measured with multi-electrode array recordings. When DHPG is bilaterally infused in vivo in the mouse striatum, treated mice display an anxiety-like behavior. Our results demonstrate that metabotropic glutamate receptors stimulation gives rise to a prolonged depression of the striatal dopaminergic transmission, through a sustained enhancement of released acetylcholine, due to the parallel long-lasting potentiation of striatal cholinergic interneurons firing. This plastic interplay between dopamine, acetylcholine, and glutamate in the dorsal striatum may be involved in anxiety-like behavior typical of several neuropsychiatric disorders.
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Affiliation(s)
- Nicola B Mercuri
- IRCCS Fondazione Santa Lucia, Laboratory of Experimental Neurology, Rome, Italy.,Department of Systems Medicine, University of Tor Vergata, Rome, Italy
| | - Mauro Federici
- IRCCS Fondazione Santa Lucia, Laboratory of Experimental Neurology, Rome, Italy
| | | | - Lorenzo Maugeri
- IRCCS Fondazione Santa Lucia, Laboratory of Experimental Neurology, Rome, Italy
| | - Sebastian L D'Addario
- IRCCS Fondazione Santa Lucia, Laboratory of Experimental Neurology, Rome, Italy.,Department of Psychology and Center Daniel Bovet, Sapienza University, Rome, Italy.,Behavioral Neuroscience PhD Programme, Sapienza University, Rome, Italy
| | - Rossella Ventura
- IRCCS Fondazione Santa Lucia, Laboratory of Experimental Neurology, Rome, Italy.,Department of Psychology and Center Daniel Bovet, Sapienza University, Rome, Italy
| | - Nicola Berretta
- IRCCS Fondazione Santa Lucia, Laboratory of Experimental Neurology, Rome, Italy
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Goel N, Peng K, Lu Y. Neuromodulation by mGluRs in Sound Localization Circuits in the Auditory Brainstem. Front Neural Circuits 2020; 14:599600. [PMID: 33224028 PMCID: PMC7674593 DOI: 10.3389/fncir.2020.599600] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/05/2020] [Indexed: 11/15/2022] Open
Abstract
The ability of humans and animals to localize the source of a sound in a complex acoustic environment facilitates communication and survival. Two cues are used for sound localization at horizontal planes, interaural time and level differences (ITD and ILD), which are analyzed by distinct neural circuits in the brainstem. Here, we review the studies on metabotropic glutamate receptor (mGluR)-mediated neuromodulation of both intrinsic and synaptic properties of brainstem neurons in these circuits. Both mammalian and avian animal models have been used, with each having their advantages that are not present in the other. For the mammalian model, we discuss mGluR neuromodulation in the ILD circuit, with an emphasis on the recent discovery of differential modulation of synaptic transmission of different transmitter release modes. For the avian model, we focus on reviewing mGluR neuromodulation in the ITD pathway, with an emphasis on tonotopic distribution and synaptic plasticity of mGluR modulation in coincidence detector neurons. Future works are proposed to further investigate the functions and mechanisms of mGluRs in the sound localization circuits.
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Affiliation(s)
- Nupur Goel
- Department of Anatomy and Neurobiology, Hearing Research Group, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Kang Peng
- Department of Anatomy and Neurobiology, Hearing Research Group, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Yong Lu
- Department of Anatomy and Neurobiology, Hearing Research Group, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, United States
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Dunn AR, Kaczorowski CC. Regulation of intrinsic excitability: Roles for learning and memory, aging and Alzheimer's disease, and genetic diversity. Neurobiol Learn Mem 2019; 164:107069. [PMID: 31442579 DOI: 10.1016/j.nlm.2019.107069] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/09/2019] [Accepted: 08/17/2019] [Indexed: 12/28/2022]
Abstract
Plasticity of intrinsic neuronal excitability facilitates learning and memory across multiple species, with aberrant modulation of this process being linked to the development of neurological symptoms in models of cognitive aging and Alzheimer's disease. Learning-related increases in intrinsic excitability of neurons occurs in a variety of brain regions, and is generally thought to promote information processing and storage through enhancement of synaptic throughput and induction of synaptic plasticity. Experience-dependent changes in intrinsic neuronal excitability rely on activity-dependent gene expression patterns, which can be influenced by genetic and environmental factors, aging, and disease. Reductions in baseline intrinsic excitability, as well as aberrant plasticity of intrinsic neuronal excitability and in some cases pathological hyperexcitability, have been associated with cognitive deficits in animal models of both normal cognitive aging and Alzheimer's disease. Genetic factors that modulate plasticity of intrinsic excitability likely underlie individual differences in cognitive function and susceptibility to cognitive decline. Thus, targeting molecular mediators that either control baseline intrinsic neuronal excitability, subserve learning-related intrinsic neuronal plasticity, and/or promote resilience may be a promising therapeutic strategy for maintaining cognitive function in aging and disease. In this review, we discuss the complementary relationship between intrinsic excitability and learning, with a particular focus on how this relationship varies as a function of age, disease state, and genetic make-up, and how targeting these factors may help to further elucidate our understanding of the role of intrinsic excitability in cognitive function and cognitive decline.
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Affiliation(s)
- Amy R Dunn
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
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Lu Y, Liu Y, Curry RJ. Activity-dependent synaptic integration and modulation of bilateral excitatory inputs in an auditory coincidence detection circuit. J Physiol 2018; 596:1981-1997. [PMID: 29572827 DOI: 10.1113/jp275735] [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: 12/18/2017] [Accepted: 03/05/2018] [Indexed: 02/05/2023] Open
Abstract
KEY POINTS Binaural excitatory inputs to coincidence detection neurons in nucleus laminaris (NL) play essential roles in interaural time difference coding for sound localization. Here, we show that the two excitatory inputs are physiologically nearly completely segregated. Synaptic integration shows linear summation of EPSPs, ensuring high efficiency of coincidence detection of the bilateral excitatory inputs. We further show that the two excitatory inputs to single NL neurons are symmetrical in synaptic strength, kinetics and short-term plasticity. Modulation of the EPSCs by metabotropic glutamate receptors (mGluRs) is identical between the two excitatory inputs, maintaining balanced bilateral excitation under neuromodulatory conditions. Unilateral hearing deprivation reduces synaptic excitation and paradoxically strengthens mGluR modulation of EPSCs, suggesting activity-dependent anti-homeostatic regulation, a novel synaptic plasticity in response to sensory manipulations. ABSTRACT Neurons in the avian nucleus laminaris (NL) receive bilateral excitatory inputs from the cochlear nucleus magnocellularis, via morphologically symmetrical dorsal (ipsilateral) and ventral (contralateral) dendrites. Using in vitro whole-cell patch recordings in chicken brainstem slices, we investigated synaptic integration and modulation of the bilateral inputs to NL under normal and hearing deprivation conditions. We found that the two excitatory inputs onto single NL neurons were nearly completely segregated, and integration of the two inputs was linear for EPSPs. The two inputs had similar synaptic strength, kinetics and short-term plasticity. EPSCs in low but not middle and high frequency neurons were suppressed by activation of group I and II metabotropic glutamate receptors (mGluR I and II), with similar modulatory strength between the ipsilateral and contralateral inputs. Unilateral hearing deprivation by cochlea removal reduced the excitatory transmission on the deprived dendritic domain of NL. Interestingly, EPSCs evoked at the deprived domain were modulated more strongly by mGluR II than at the counterpart domain that received intact input in low frequency neurons, suggesting anti-homeostatic regulation. This was supported by a stronger expression of mGluR II protein on the deprived neuropils of NL. Under mGluR II modulation, EPSCs on the deprived input show transient synaptic facilitation, forming a striking contrast with normal hearing conditions under which pure synaptic depression is observed. These results demonstrate physiological symmetry and thus balanced bilateral excitatory inputs to NL neurons. The activity-dependent anti-homeostatic plasticity of mGluR modulation constitutes a novel mechanism regulating synaptic transmission in response to sensory input manipulations.
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Affiliation(s)
- Yong Lu
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA.,School of Biomedical Sciences, Kent State University, Kent, OH, 44240, USA
| | - Yuwei Liu
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | - Rebecca J Curry
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA.,School of Biomedical Sciences, Kent State University, Kent, OH, 44240, USA
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7
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Tang ZQ, Lu Y. Anatomy and Physiology of Metabotropic Glutamate Receptors in Mammalian and Avian Auditory System. ACTA ACUST UNITED AC 2018; 1. [PMID: 30854519 DOI: 10.24966/tap-7752/100001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Glutamate, as the major excitatory neurotransmitter used in the vertebrate brain, activates ionotropic and metabotropic glutamate receptors (iGluRs and mGluRs), which mediate fast and slow neuronal actions, respectively. mGluRs play important modulatory roles in many brain areas, forming potential targets for drugs developed to treat brain disorders. Here, we review studies on mGluRs in the mammalian and avian auditory system. Although anatomical expression of mGluRs in the cochlear nucleus has been well characterized, data for other auditory nuclei await more systematic investigations especially at the electron microscopy level. The physiology of mGluRs has been extensively studied using in vitro brain slice preparations, with a focus on the auditory circuitry in the brainstem. These in vitro physiological studies have demonstrated that mGluRs participate in synaptic transmission, regulate ionic homeostasis, induce synaptic plasticity, and maintain the balance between Excitation and Inhibition (E/I) in a variety of auditory structures. However, the modulatory roles of mGluRs in auditory processing remain largely unclear at the system and behavioral levels, and the functions of mGluRs in auditory disorders remain entirely unknown.
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Affiliation(s)
- Zheng-Quan Tang
- Oregon Hearing Research Center, Vollum Institute, Oregon Health and Science University, Oregon, USA
| | - Yong Lu
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Ohio, USA
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Koren D, Grove JCR, Wei W. Cross-compartmental Modulation of Dendritic Signals for Retinal Direction Selectivity. Neuron 2017; 95:914-927.e4. [PMID: 28781167 DOI: 10.1016/j.neuron.2017.07.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 06/08/2017] [Accepted: 07/19/2017] [Indexed: 11/19/2022]
Abstract
Compartmentalized signaling in dendritic subdomains is critical for the function of many central neurons. In the retina, individual dendritic sectors of a starburst amacrine cell (SAC) are preferentially activated by different directions of linear motion, indicating limited signal propagation between the sectors. However, the mechanism that regulates this propagation is poorly understood. Here, we find that metabotropic glutamate receptor 2 (mGluR2) signaling, which acts on voltage-gated calcium channels in SACs, selectively restricts cross-sector signal propagation in SACs, but does not affect local dendritic computation within individual sectors. mGluR2 signaling ensures sufficient electrotonic isolation of dendritic sectors to prevent their depolarization during non-preferred motion, yet enables controlled multicompartmental signal integration that enhances responses to preferred motion. Furthermore, mGluR2-mediated dendritic compartmentalization in SACs is important for the functional output of direction-selective ganglion cells (DSGCs). Therefore, our results directly link modulation of dendritic compartmentalization to circuit-level encoding of motion direction in the retina.
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Affiliation(s)
- David Koren
- Department of Neurobiology, The University of Chicago, Chicago, IL 60637, USA; Interdisciplinary Scientist Training Program, The University of Chicago, Chicago, IL 60637, USA
| | - James C R Grove
- Department of Neurobiology, The University of Chicago, Chicago, IL 60637, USA
| | - Wei Wei
- Department of Neurobiology, The University of Chicago, Chicago, IL 60637, USA.
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