1
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Lohse M, King AJ, Willmore BDB. Subcortical origin of nonlinear sound encoding in auditory cortex. Curr Biol 2024; 34:3405-3415.e5. [PMID: 39032492 DOI: 10.1016/j.cub.2024.06.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 06/05/2024] [Accepted: 06/21/2024] [Indexed: 07/23/2024]
Abstract
A major challenge in neuroscience is to understand how neural representations of sensory information are transformed by the network of ascending and descending connections in each sensory system. By recording from neurons at several levels of the auditory pathway, we show that much of the nonlinear encoding of complex sounds in auditory cortex can be explained by transformations in the midbrain and thalamus. Modeling cortical neurons in terms of their inputs across these subcortical populations enables their responses to be predicted with unprecedented accuracy. By contrast, subcortical responses cannot be predicted from descending cortical inputs, indicating that ascending transformations are irreversible, resulting in increasingly lossy, higher-order representations across the auditory pathway. Rather, auditory cortex selectively modulates the nonlinear aspects of thalamic auditory responses and the functional coupling between subcortical neurons without affecting the linear encoding of sound. These findings reveal the fundamental role of subcortical transformations in shaping cortical responses.
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Affiliation(s)
- Michael Lohse
- Sainsbury Wellcome Centre for Neural Circuits and Behaviour, University College London, London W1T 4JG, UK; Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, UK.
| | - Andrew J King
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, UK.
| | - Ben D B Willmore
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, UK.
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2
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Quass GL, Rogalla MM, Ford AN, Apostolides PF. Mixed Representations of Sound and Action in the Auditory Midbrain. J Neurosci 2024; 44:e1831232024. [PMID: 38918064 PMCID: PMC11270520 DOI: 10.1523/jneurosci.1831-23.2024] [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] [Revised: 06/05/2024] [Accepted: 06/14/2024] [Indexed: 06/27/2024] Open
Abstract
Linking sensory input and its consequences is a fundamental brain operation. During behavior, the neural activity of neocortical and limbic systems often reflects dynamic combinations of sensory and task-dependent variables, and these "mixed representations" are suggested to be important for perception, learning, and plasticity. However, the extent to which such integrative computations might occur outside of the forebrain is less clear. Here, we conduct cellular-resolution two-photon Ca2+ imaging in the superficial "shell" layers of the inferior colliculus (IC), as head-fixed mice of either sex perform a reward-based psychometric auditory task. We find that the activity of individual shell IC neurons jointly reflects auditory cues, mice's actions, and behavioral trial outcomes, such that trajectories of neural population activity diverge depending on mice's behavioral choice. Consequently, simple classifier models trained on shell IC neuron activity can predict trial-by-trial outcomes, even when training data are restricted to neural activity occurring prior to mice's instrumental actions. Thus, in behaving mice, auditory midbrain neurons transmit a population code that reflects a joint representation of sound, actions, and task-dependent variables.
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Affiliation(s)
- Gunnar L Quass
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Meike M Rogalla
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Alexander N Ford
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Pierre F Apostolides
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
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3
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Shi K, Quass GL, Rogalla MM, Ford AN, Czarny JE, Apostolides PF. Population coding of time-varying sounds in the nonlemniscal inferior colliculus. J Neurophysiol 2024; 131:842-864. [PMID: 38505907 PMCID: PMC11381119 DOI: 10.1152/jn.00013.2024] [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: 01/10/2024] [Revised: 02/29/2024] [Accepted: 03/15/2024] [Indexed: 03/21/2024] Open
Abstract
The inferior colliculus (IC) of the midbrain is important for complex sound processing, such as discriminating conspecific vocalizations and human speech. The IC's nonlemniscal, dorsal "shell" region is likely important for this process, as neurons in these layers project to higher-order thalamic nuclei that subsequently funnel acoustic signals to the amygdala and nonprimary auditory cortices, forebrain circuits important for vocalization coding in a variety of mammals, including humans. However, the extent to which shell IC neurons transmit acoustic features necessary to discern vocalizations is less clear, owing to the technical difficulty of recording from neurons in the IC's superficial layers via traditional approaches. Here, we use two-photon Ca2+ imaging in mice of either sex to test how shell IC neuron populations encode the rate and depth of amplitude modulation, important sound cues for speech perception. Most shell IC neurons were broadly tuned, with a low neurometric discrimination of amplitude modulation rate; only a subset was highly selective to specific modulation rates. Nevertheless, neural network classifier trained on fluorescence data from shell IC neuron populations accurately classified amplitude modulation rate, and decoding accuracy was only marginally reduced when highly tuned neurons were omitted from training data. Rather, classifier accuracy increased monotonically with the modulation depth of the training data, such that classifiers trained on full-depth modulated sounds had median decoding errors of ∼0.2 octaves. Thus, shell IC neurons may transmit time-varying signals via a population code, with perhaps limited reliance on the discriminative capacity of any individual neuron.NEW & NOTEWORTHY The IC's shell layers originate a "nonlemniscal" pathway important for perceiving vocalization sounds. However, prior studies suggest that individual shell IC neurons are broadly tuned and have high response thresholds, implying a limited reliability of efferent signals. Using Ca2+ imaging, we show that amplitude modulation is accurately represented in the population activity of shell IC neurons. Thus, downstream targets can read out sounds' temporal envelopes from distributed rate codes transmitted by populations of broadly tuned neurons.
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Affiliation(s)
- Kaiwen Shi
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Gunnar L Quass
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Meike M Rogalla
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Alexander N Ford
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Jordyn E Czarny
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Pierre F Apostolides
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States
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4
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Drotos AC, Roberts MT. Identifying neuron types and circuit mechanisms in the auditory midbrain. Hear Res 2024; 442:108938. [PMID: 38141518 PMCID: PMC11000261 DOI: 10.1016/j.heares.2023.108938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 11/27/2023] [Accepted: 12/18/2023] [Indexed: 12/25/2023]
Abstract
The inferior colliculus (IC) is a critical computational hub in the central auditory pathway. From its position in the midbrain, the IC receives nearly all the ascending output from the lower auditory brainstem and provides the main source of auditory information to the thalamocortical system. In addition to being a crossroads for auditory circuits, the IC is rich with local circuits and contains more than five times as many neurons as the nuclei of the lower auditory brainstem combined. These results hint at the enormous computational power of the IC, and indeed, systems-level studies have identified numerous important transformations in sound coding that occur in the IC. However, despite decades of effort, the cellular mechanisms underlying IC computations and how these computations change following hearing loss have remained largely impenetrable. In this review, we argue that this challenge persists due to the surprisingly difficult problem of identifying the neuron types and circuit motifs that comprise the IC. After summarizing the extensive evidence pointing to a diversity of neuron types in the IC, we highlight the successes of recent efforts to parse this complexity using molecular markers to define neuron types. We conclude by arguing that the discovery of molecularly identifiable neuron types ushers in a new era for IC research marked by molecularly targeted recordings and manipulations. We propose that the ability to reproducibly investigate IC circuits at the neuronal level will lead to rapid advances in understanding the fundamental mechanisms driving IC computations and how these mechanisms shift following hearing loss.
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Affiliation(s)
- Audrey C Drotos
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, United States
| | - Michael T Roberts
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, United States; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, 48109, United States.
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5
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Quass GL, Rogalla MM, Ford AN, Apostolides PF. Mixed representations of sound and action in the auditory midbrain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.19.558449. [PMID: 37786676 PMCID: PMC10541616 DOI: 10.1101/2023.09.19.558449] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Linking sensory input and its consequences is a fundamental brain operation. Accordingly, neural activity of neo-cortical and limbic systems often reflects dynamic combinations of sensory and behaviorally relevant variables, and these "mixed representations" are suggested to be important for perception, learning, and plasticity. However, the extent to which such integrative computations might occur in brain regions upstream of the forebrain is less clear. Here, we conduct cellular-resolution 2-photon Ca2+ imaging in the superficial "shell" layers of the inferior colliculus (IC), as head-fixed mice of either sex perform a reward-based psychometric auditory task. We find that the activity of individual shell IC neurons jointly reflects auditory cues and mice's actions, such that trajectories of neural population activity diverge depending on mice's behavioral choice. Consequently, simple classifier models trained on shell IC neuron activity can predict trial-by-trial outcomes, even when training data are restricted to neural activity occurring prior to mice's instrumental actions. Thus in behaving animals, auditory midbrain neurons transmit a population code that reflects a joint representation of sound and action.
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Affiliation(s)
- GL Quass
- Kresge Hearing Research Institute, Department of Otolaryngology – Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - MM Rogalla
- Kresge Hearing Research Institute, Department of Otolaryngology – Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - AN Ford
- Kresge Hearing Research Institute, Department of Otolaryngology – Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - PF Apostolides
- Kresge Hearing Research Institute, Department of Otolaryngology – Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
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6
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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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7
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Shi K, Quass GL, Rogalla MM, Ford AN, Czarny JE, Apostolides PF. Population coding of time-varying sounds in the non-lemniscal Inferior Colliculus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.14.553263. [PMID: 37645904 PMCID: PMC10461978 DOI: 10.1101/2023.08.14.553263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The inferior colliculus (IC) of the midbrain is important for complex sound processing, such as discriminating conspecific vocalizations and human speech. The IC's non-lemniscal, dorsal "shell" region is likely important for this process, as neurons in these layers project to higher-order thalamic nuclei that subsequently funnel acoustic signals to the amygdala and non-primary auditory cortices; forebrain circuits important for vocalization coding in a variety of mammals, including humans. However, the extent to which shell IC neurons transmit acoustic features necessary to discern vocalizations is less clear, owing to the technical difficulty of recording from neurons in the IC's superficial layers via traditional approaches. Here we use 2-photon Ca2+ imaging in mice of either sex to test how shell IC neuron populations encode the rate and depth of amplitude modulation, important sound cues for speech perception. Most shell IC neurons were broadly tuned, with a low neurometric discrimination of amplitude modulation rate; only a subset were highly selective to specific modulation rates. Nevertheless, neural network classifier trained on fluorescence data from shell IC neuron populations accurately classified amplitude modulation rate, and decoding accuracy was only marginally reduced when highly tuned neurons were omitted from training data. Rather, classifier accuracy increased monotonically with the modulation depth of the training data, such that classifiers trained on full-depth modulated sounds had median decoding errors of ~0.2 octaves. Thus, shell IC neurons may transmit time-varying signals via a population code, with perhaps limited reliance on the discriminative capacity of any individual neuron.
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Affiliation(s)
- Kaiwen Shi
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Gunnar L. Quass
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Meike M. Rogalla
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Alexander N. Ford
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Jordyn E. Czarny
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Pierre F. Apostolides
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48109
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Schmitt TTX, Andrea KMA, Wadle SL, Hirtz JJ. Distinct topographic organization and network activity patterns of corticocollicular neurons within layer 5 auditory cortex. Front Neural Circuits 2023; 17:1210057. [PMID: 37521334 PMCID: PMC10372447 DOI: 10.3389/fncir.2023.1210057] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/22/2023] [Indexed: 08/01/2023] Open
Abstract
The auditory cortex (AC) modulates the activity of upstream pathways in the auditory brainstem via descending (corticofugal) projections. This feedback system plays an important role in the plasticity of the auditory system by shaping response properties of neurons in many subcortical nuclei. The majority of layer (L) 5 corticofugal neurons project to the inferior colliculus (IC). This corticocollicular (CC) pathway is involved in processing of complex sounds, auditory-related learning, and defense behavior. Partly due to their location in deep cortical layers, CC neuron population activity patterns within neuronal AC ensembles remain poorly understood. We employed two-photon imaging to record the activity of hundreds of L5 neurons in anesthetized as well as awake animals. CC neurons are broader tuned than other L5 pyramidal neurons and display weaker topographic order in core AC subfields. Network activity analyses revealed stronger clusters of CC neurons compared to non-CC neurons, which respond more reliable and integrate information over larger distances. However, results obtained from secondary auditory cortex (A2) differed considerably. Here CC neurons displayed similar or higher topography, depending on the subset of neurons analyzed. Furthermore, specifically in A2, CC activity clusters formed in response to complex sounds were spatially more restricted compared to other L5 neurons. Our findings indicate distinct network mechanism of CC neurons in analyzing sound properties with pronounced subfield differences, demonstrating that the topography of sound-evoked responses within AC is neuron-type dependent.
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9
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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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10
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Lawlor J, Wohlgemuth MJ, Moss CF, Kuchibhotla KV. Spatially clustered neurons encode vocalization categories in the bat midbrain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.14.545029. [PMID: 37398454 PMCID: PMC10312733 DOI: 10.1101/2023.06.14.545029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Rapid categorization of vocalizations enables adaptive behavior across species. While categorical perception is thought to arise in the neocortex, humans and other animals could benefit from functional organization of ethologically-relevant sounds at earlier stages in the auditory hierarchy. Here, we developed two-photon calcium imaging in the awake echolocating bat (Eptesicus fuscus) to study encoding of sound meaning in the Inferior Colliculus, which is as few as two synapses from the inner ear. Echolocating bats produce and interpret frequency sweep-based vocalizations for social communication and navigation. Auditory playback experiments demonstrated that individual neurons responded selectively to social or navigation calls, enabling robust population-level decoding across categories. Strikingly, category-selective neurons formed spatial clusters, independent of tonotopy within the IC. These findings support a revised view of categorical processing in which specified channels for ethologically-relevant sounds are spatially segregated early in the auditory hierarchy, enabling rapid subcortical organization of call meaning.
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Affiliation(s)
- Jennifer Lawlor
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, 21218, USA
- Johns Hopkins Kavli Neuroscience Discovery Institute, Baltimore, MD, 21218, MD
| | | | - Cynthia F. Moss
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, 21218, USA
- Johns Hopkins Kavli Neuroscience Discovery Institute, Baltimore, MD, 21218, MD
- The Solomon Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Kishore V. Kuchibhotla
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, 21218, USA
- Johns Hopkins Kavli Neuroscience Discovery Institute, Baltimore, MD, 21218, MD
- The Solomon Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
- Lead contact
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11
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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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12
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McAlpine D, de Hoz L. Listening loops and the adapting auditory brain. Front Neurosci 2023; 17:1081295. [PMID: 37008228 PMCID: PMC10060829 DOI: 10.3389/fnins.2023.1081295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/17/2023] [Indexed: 03/18/2023] Open
Abstract
Analysing complex auditory scenes depends in part on learning the long-term statistical structure of sounds comprising those scenes. One way in which the listening brain achieves this is by analysing the statistical structure of acoustic environments over multiple time courses and separating background from foreground sounds. A critical component of this statistical learning in the auditory brain is the interplay between feedforward and feedback pathways—“listening loops”—connecting the inner ear to higher cortical regions and back. These loops are likely important in setting and adjusting the different cadences over which learned listening occurs through adaptive processes that tailor neural responses to sound environments that unfold over seconds, days, development, and the life-course. Here, we posit that exploring listening loops at different scales of investigation—from in vivo recording to human assessment—their role in detecting different timescales of regularity, and the consequences this has for background detection, will reveal the fundamental processes that transform hearing into the essential task of listening.
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Affiliation(s)
- David McAlpine
- Department of Linguistics, Macquarie University, Sydney, NSW, Australia
- *Correspondence: David McAlpine,
| | - Livia de Hoz
- Neuroscience Research Center, Charité – Universitätsmedizin Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
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13
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Kersbergen CJ, Babola TA, Rock J, Bergles DE. Developmental spontaneous activity promotes formation of sensory domains, frequency tuning and proper gain in central auditory circuits. Cell Rep 2022; 41:111649. [PMID: 36384119 PMCID: PMC9730452 DOI: 10.1016/j.celrep.2022.111649] [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: 03/26/2022] [Revised: 08/24/2022] [Accepted: 10/20/2022] [Indexed: 11/17/2022] Open
Abstract
Neurons that process sensory information exhibit bursts of electrical activity during development, providing early training to circuits that will later encode similar features of the external world. In the mammalian auditory system, this intrinsically generated activity emerges from the cochlea prior to hearing onset, but its role in maturation of auditory circuitry remains poorly understood. We show that selective suppression of cochlear supporting cell spontaneous activity disrupts patterned burst firing of central auditory neurons without affecting cell survival or acoustic thresholds. However, neurons in the inferior colliculus of these mice exhibit enhanced acoustic sensitivity and broader frequency tuning, resulting in wider isofrequency laminae. Despite this enhanced neural responsiveness, total tone-responsive regions in the auditory cortex are substantially smaller. Thus, disruption of pre-hearing cochlear activity causes profound changes in neural encoding of sound, with important implications for restoration of hearing in individuals who experience reduced activity during this critical developmental period.
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Affiliation(s)
- Calvin J Kersbergen
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | - Travis A Babola
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | | | - Dwight E Bergles
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA; Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, USA.
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14
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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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15
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Song X, Guo Y, Chen C, Wang X. A silent two-photon imaging system for studying in vivo auditory neuronal functions. LIGHT, SCIENCE & APPLICATIONS 2022; 11:96. [PMID: 35422090 PMCID: PMC9010453 DOI: 10.1038/s41377-022-00783-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 03/28/2022] [Accepted: 03/30/2022] [Indexed: 05/04/2023]
Abstract
Two-photon laser-scanning microscopy has become an essential tool for imaging neuronal functions in vivo and has been applied to different parts of the neural system, including the auditory system. However, many components of a two-photon microscope, such as galvanometer-based laser scanners, generate mechanical vibrations and thus acoustic artifacts, making it difficult to interpret auditory responses from recorded neurons. Here, we report the development of a silent two-photon imaging system and its applications in the common marmoset (Callithrix Jacchus), a non-human primate species sharing a similar hearing range with humans. By utilizing an orthogonal pair of acousto-optical deflectors (AODs), full-frame raster scanning at video rate was achieved without introducing mechanical vibrations. Imaging depth can be optically controlled by adjusting the chirping speed on the AODs without any mechanical motion along the Z-axis. Furthermore, all other sound-generating components of the system were acoustically isolated, leaving the noise floor of the working system below the marmoset's hearing threshold. Imaging with the system in awake marmosets revealed many auditory cortex neurons that exhibited maximal responses at low sound levels, which were not possible to study using traditional two-photon imaging systems. This is the first demonstration of a silent two-photon imaging system that is capable of imaging auditory neuronal functions in vivo without acoustic artifacts. This capacity opens new opportunities for a better understanding of auditory functions in the brain and helps isolate animal behavior from microscope-generated acoustic interference.
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Affiliation(s)
- Xindong Song
- Laboratory of Auditory Neurophysiology, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
| | - Yueqi Guo
- Laboratory of Auditory Neurophysiology, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Chenggang Chen
- Laboratory of Auditory Neurophysiology, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Xiaoqin Wang
- Laboratory of Auditory Neurophysiology, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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16
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Liu M, Dai J, Zhou M, Liu J, Ge X, Wang N, Zhang J. Mini-review: The neural circuits of the non-lemniscal inferior colliculus. Neurosci Lett 2022; 776:136567. [DOI: 10.1016/j.neulet.2022.136567] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 02/07/2022] [Accepted: 03/03/2022] [Indexed: 01/12/2023]
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17
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Oberle HM, Ford AN, Dileepkumar D, Czarny J, Apostolides PF. Synaptic mechanisms of top-down control in the non-lemniscal inferior colliculus. eLife 2022; 10:e72730. [PMID: 34989674 PMCID: PMC8735864 DOI: 10.7554/elife.72730] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 12/19/2021] [Indexed: 01/05/2023] Open
Abstract
Corticofugal projections to evolutionarily ancient, subcortical structures are ubiquitous across mammalian sensory systems. These 'descending' pathways enable the neocortex to control ascending sensory representations in a predictive or feedback manner, but the underlying cellular mechanisms are poorly understood. Here, we combine optogenetic approaches with in vivo and in vitro patch-clamp electrophysiology to study the projection from mouse auditory cortex to the inferior colliculus (IC), a major descending auditory pathway that controls IC neuron feature selectivity, plasticity, and auditory perceptual learning. Although individual auditory cortico-collicular synapses were generally weak, IC neurons often integrated inputs from multiple corticofugal axons that generated reliable, tonic depolarizations even during prolonged presynaptic activity. Latency measurements in vivo showed that descending signals reach the IC within 30 ms of sound onset, which in IC neurons corresponded to the peak of synaptic depolarizations evoked by short sounds. Activating ascending and descending pathways at latencies expected in vivo caused a NMDA receptor-dependent, supralinear excitatory postsynaptic potential summation, indicating that descending signals can nonlinearly amplify IC neurons' moment-to-moment acoustic responses. Our results shed light upon the synaptic bases of descending sensory control and imply that heterosynaptic cooperativity contributes to the auditory cortico-collicular pathway's role in plasticity and perceptual learning.
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Affiliation(s)
- Hannah M Oberle
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
- Neuroscience Graduate Program, University of MichiganAnn ArborUnited States
| | - Alexander N Ford
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
| | - Deepak Dileepkumar
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
| | - Jordyn Czarny
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
| | - Pierre F Apostolides
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
- Molecular and Integrative Physiology, University of Michigan Medical SchoolAnn ArborUnited States
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18
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Lohse M, Dahmen JC, Bajo VM, King AJ. Subcortical circuits mediate communication between primary sensory cortical areas in mice. Nat Commun 2021; 12:3916. [PMID: 34168153 PMCID: PMC8225818 DOI: 10.1038/s41467-021-24200-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 06/02/2021] [Indexed: 12/20/2022] Open
Abstract
Integration of information across the senses is critical for perception and is a common property of neurons in the cerebral cortex, where it is thought to arise primarily from corticocortical connections. Much less is known about the role of subcortical circuits in shaping the multisensory properties of cortical neurons. We show that stimulation of the whiskers causes widespread suppression of sound-evoked activity in mouse primary auditory cortex (A1). This suppression depends on the primary somatosensory cortex (S1), and is implemented through a descending circuit that links S1, via the auditory midbrain, with thalamic neurons that project to A1. Furthermore, a direct pathway from S1 has a facilitatory effect on auditory responses in higher-order thalamic nuclei that project to other brain areas. Crossmodal corticofugal projections to the auditory midbrain and thalamus therefore play a pivotal role in integrating multisensory signals and in enabling communication between different sensory cortical areas.
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Affiliation(s)
- Michael Lohse
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, UK.
- Sainsbury Wellcome Centre, London, UK.
| | - Johannes C Dahmen
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, UK
| | - Victoria M Bajo
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, UK
| | - Andrew J King
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, UK.
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19
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Asilador A, Llano DA. Top-Down Inference in the Auditory System: Potential Roles for Corticofugal Projections. Front Neural Circuits 2021; 14:615259. [PMID: 33551756 PMCID: PMC7862336 DOI: 10.3389/fncir.2020.615259] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/17/2020] [Indexed: 01/28/2023] Open
Abstract
It has become widely accepted that humans use contextual information to infer the meaning of ambiguous acoustic signals. In speech, for example, high-level semantic, syntactic, or lexical information shape our understanding of a phoneme buried in noise. Most current theories to explain this phenomenon rely on hierarchical predictive coding models involving a set of Bayesian priors emanating from high-level brain regions (e.g., prefrontal cortex) that are used to influence processing at lower-levels of the cortical sensory hierarchy (e.g., auditory cortex). As such, virtually all proposed models to explain top-down facilitation are focused on intracortical connections, and consequently, subcortical nuclei have scarcely been discussed in this context. However, subcortical auditory nuclei receive massive, heterogeneous, and cascading descending projections at every level of the sensory hierarchy, and activation of these systems has been shown to improve speech recognition. It is not yet clear whether or how top-down modulation to resolve ambiguous sounds calls upon these corticofugal projections. Here, we review the literature on top-down modulation in the auditory system, primarily focused on humans and cortical imaging/recording methods, and attempt to relate these findings to a growing animal literature, which has primarily been focused on corticofugal projections. We argue that corticofugal pathways contain the requisite circuitry to implement predictive coding mechanisms to facilitate perception of complex sounds and that top-down modulation at early (i.e., subcortical) stages of processing complement modulation at later (i.e., cortical) stages of processing. Finally, we suggest experimental approaches for future studies on this topic.
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Affiliation(s)
- Alexander Asilador
- Neuroscience Program, The University of Illinois at Urbana-Champaign, Champaign, IL, United States
- Beckman Institute for Advanced Science and Technology, Urbana, IL, United States
| | - Daniel A. Llano
- Neuroscience Program, The University of Illinois at Urbana-Champaign, Champaign, IL, United States
- Beckman Institute for Advanced Science and Technology, Urbana, IL, United States
- Molecular and Integrative Physiology, The University of Illinois at Urbana-Champaign, Champaign, IL, United States
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20
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Henschke JU, Pakan JM. Disynaptic cerebrocerebellar pathways originating from multiple functionally distinct cortical areas. eLife 2020; 9:59148. [PMID: 32795386 PMCID: PMC7428308 DOI: 10.7554/elife.59148] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/28/2020] [Indexed: 12/31/2022] Open
Abstract
The cerebral cortex and cerebellum both play important roles in sensorimotor processing, however, precise connections between these major brain structures remain elusive. Using anterograde mono-trans-synaptic tracing, we elucidate cerebrocerebellar pathways originating from primary motor, sensory, and association cortex. We confirm a highly organized topography of corticopontine projections in mice; however, we found no corticopontine projections originating from primary auditory cortex and detail several potential extra-pontine cerebrocerebellar pathways. The cerebellar hemispheres were the major target of resulting disynaptic mossy fiber terminals, but we also found at least sparse cerebrocerebellar projections to every lobule of the cerebellum. Notably, projections originating from association cortex resulted in less laterality than primary sensory/motor cortices. Within molecularly defined cerebellar modules we found spatial overlap of mossy fiber terminals, originating from functionally distinct cortical areas, within crus I, paraflocculus, and vermal regions IV/V and VI - highlighting these regions as potential hubs for multimodal cortical influence.
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Affiliation(s)
- Julia U Henschke
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke-University, Magdeburg, Germany.,German Centre for Neurodegenerative Diseases, Magdeburg, Germany
| | - Janelle Mp Pakan
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke-University, Magdeburg, Germany.,German Centre for Neurodegenerative Diseases, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Universitätsplatz, Magdeburg, Germany
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21
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Gaucher Q, Panniello M, Ivanov AZ, Dahmen JC, King AJ, Walker KM. Complexity of frequency receptive fields predicts tonotopic variability across species. eLife 2020; 9:53462. [PMID: 32420865 PMCID: PMC7269667 DOI: 10.7554/elife.53462] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 05/18/2020] [Indexed: 12/17/2022] Open
Abstract
Primary cortical areas contain maps of sensory features, including sound frequency in primary auditory cortex (A1). Two-photon calcium imaging in mice has confirmed the presence of these global tonotopic maps, while uncovering an unexpected local variability in the stimulus preferences of individual neurons in A1 and other primary regions. Here we show that local heterogeneity of frequency preferences is not unique to rodents. Using two-photon calcium imaging in layers 2/3, we found that local variance in frequency preferences is equivalent in ferrets and mice. Neurons with multipeaked frequency tuning are less spatially organized than those tuned to a single frequency in both species. Furthermore, we show that microelectrode recordings may describe a smoother tonotopic arrangement due to a sampling bias towards neurons with simple frequency tuning. These results help explain previous inconsistencies in cortical topography across species and recording techniques.
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Affiliation(s)
- Quentin Gaucher
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Mariangela Panniello
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Aleksandar Z Ivanov
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Johannes C Dahmen
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Andrew J King
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Kerry Mm Walker
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
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22
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Behavioral anatomy of a hunt : Using dynamic real-world paradigm and computer vision to compare human user-generated strategies with prey movement varying in predictability. Atten Percept Psychophys 2020; 82:3112-3123. [PMID: 32406004 PMCID: PMC7381454 DOI: 10.3758/s13414-020-02016-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
It is commonly thought that the mind constructs predictive models of the environment to plan an appropriate behavioral response. Therefore a more predictable environment should entail better performance, and prey should move in an unpredictable (random) manner to evade capture, known as protean motion. To test this, we created a novel experimental design and analysis in which human participants took the role of predator or prey. The predator was set the task of capturing the prey, while the prey was set the task of escaping. Participants performed this task standing on separate sides of a board and controlling a marker representing them. In three conditions, the prey followed a pattern of movement with varying predictability (predictable, semi-random, and random) and in one condition moved autonomously (user generated). The user-generated condition illustrated a naturalistic, dynamic environment involving a purposeful agent whose degree of predictability was not known in advance. The average distance between participants was measured through a video analysis custom-built in MATLAB. The user-generated condition had the largest average distance. This indicated that, rather than moving randomly (protean motion), humans may naturally employ a cybernetic escape strategy that dynamically maximizes perceived distance, regardless of the predictability of this strategy.
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23
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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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24
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Blackwell JM, Lesicko AMH, Rao W, De Biasi M, Geffen MN. Auditory cortex shapes sound responses in the inferior colliculus. eLife 2020; 9:e51890. [PMID: 32003747 PMCID: PMC7062464 DOI: 10.7554/elife.51890] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 01/31/2020] [Indexed: 12/30/2022] Open
Abstract
The extensive feedback from the auditory cortex (AC) to the inferior colliculus (IC) supports critical aspects of auditory behavior but has not been extensively characterized. Previous studies demonstrated that activity in IC is altered by focal electrical stimulation and pharmacological inactivation of AC, but these methods lack the ability to selectively manipulate projection neurons. We measured the effects of selective optogenetic modulation of cortico-collicular feedback projections on IC sound responses in mice. Activation of feedback increased spontaneous activity and decreased stimulus selectivity in IC, whereas suppression had no effect. To further understand how microcircuits in AC may control collicular activity, we optogenetically modulated the activity of different cortical neuronal subtypes, specifically parvalbumin-positive (PV) and somatostatin-positive (SST) inhibitory interneurons. We found that modulating the activity of either type of interneuron did not affect IC sound-evoked activity. Combined, our results identify that activation of excitatory projections, but not inhibition-driven changes in cortical activity, affects collicular sound responses.
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Affiliation(s)
- Jennifer M Blackwell
- Department of OtorhinolaryngologyUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of Neurobiology and BehaviorStony Brook UniversityStony BrookUnited States
| | - Alexandria MH Lesicko
- Department of OtorhinolaryngologyUniversity of PennsylvaniaPhiladelphiaUnited States
| | - Winnie Rao
- Department of OtorhinolaryngologyUniversity of PennsylvaniaPhiladelphiaUnited States
| | - Mariella De Biasi
- Department of PsychiatryUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of Systems Pharmacology and Experimental TherapeuticsUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of NeuroscienceUniversity of PennsylvaniaPhiladelphiaUnited States
| | - Maria N Geffen
- Department of OtorhinolaryngologyUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of NeuroscienceUniversity of PennsylvaniaPhiladelphiaUnited States
- Department of NeurologyUniversity of PennsylvaniaPhiladelphiaUnited States
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25
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Lohse M, Bajo VM, King AJ, Willmore BDB. Neural circuits underlying auditory contrast gain control and their perceptual implications. Nat Commun 2020; 11:324. [PMID: 31949136 PMCID: PMC6965083 DOI: 10.1038/s41467-019-14163-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 12/19/2019] [Indexed: 11/09/2022] Open
Abstract
Neural adaptation enables sensory information to be represented optimally in the brain despite large fluctuations over time in the statistics of the environment. Auditory contrast gain control represents an important example, which is thought to arise primarily from cortical processing. Here we show that neurons in the auditory thalamus and midbrain of mice show robust contrast gain control, and that this is implemented independently of cortical activity. Although neurons at each level exhibit contrast gain control to similar degrees, adaptation time constants become longer at later stages of the processing hierarchy, resulting in progressively more stable representations. We also show that auditory discrimination thresholds in human listeners compensate for changes in contrast, and that the strength of this perceptual adaptation can be predicted from physiological measurements. Contrast adaptation is therefore a robust property of both the subcortical and cortical auditory system and accounts for the short-term adaptability of perceptual judgments.
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Affiliation(s)
- Michael Lohse
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
| | - Victoria M Bajo
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Andrew J King
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
| | - Ben D B Willmore
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, OX1 3PT, UK
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26
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Combining mGRASP and Optogenetics Enables High-Resolution Functional Mapping of Descending Cortical Projections. Cell Rep 2020; 24:1071-1080. [PMID: 30044974 PMCID: PMC6083038 DOI: 10.1016/j.celrep.2018.06.076] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 03/23/2018] [Accepted: 06/18/2018] [Indexed: 11/25/2022] Open
Abstract
We have applied optogenetics and mGRASP, a light microscopy technique that labels synaptic contacts, to map the number and strength of defined corticocollicular (CC) connections. Using mGRASP, we show that CC projections form small, medium, and large synapses, and both the number and the distribution of synapse size vary among the IC regions. Using optogenetics, we show that low-frequency stimulation of CC axons expressing channelrhodopsin produces prolonged elevations of the CC miniature EPSC (mEPSC) rate. Functional analysis of CC mEPSCs reveals small-, medium-, and large-amplitude events that mirror the synaptic distributions observed with mGRASP. Our results reveal that descending ipsilateral projections dominate CC feedback via an increased number of large synaptic contacts, especially onto the soma of IC neurons. This study highlights the feasibility of combining microscopy (i.e., mGRASP) and optogenetics to reveal synaptic weighting of defined projections at the level of single neurons, enabling functional connectomic mapping in diverse neural circuits. Optogenetic axonal stimulation causes prolonged increases in quantal synaptic release Quantal and anatomical measures of synapse strength directly correspond Strength and cellular location of cortical inputs to midbrain are region specific
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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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Chen C, Song S. Differential cell-type dependent brain state modulations of sensory representations in the non-lemniscal mouse inferior colliculus. Commun Biol 2019; 2:356. [PMID: 31583287 PMCID: PMC6769006 DOI: 10.1038/s42003-019-0602-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 08/23/2019] [Indexed: 02/01/2023] Open
Abstract
Sensory responses of the neocortex are strongly influenced by brain state changes. However, it remains unclear whether and how the sensory responses of the midbrain are affected. Here we addressed this issue by using in vivo two-photon calcium imaging to monitor the spontaneous and sound-evoked activities in the mouse inferior colliculus (IC). We developed a method enabling us to image the first layer of non-lemniscal IC (IC shell L1) in awake behaving mice. Compared with the awake state, spectral tuning selectivity of excitatory neurons was decreased during isoflurane anesthesia. Calcium imaging in behaving animals revealed that activities of inhibitory neurons were highly correlated with locomotion. Compared with stationary periods, spectral tuning selectivity of excitatory neurons was increased during locomotion. Taken together, our studies reveal that neuronal activities in the IC shell L1 are brain state dependent, whereas the brain state modulates the excitatory and inhibitory neurons differentially.
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Affiliation(s)
- Chenggang Chen
- Tsinghua Laboratory of Brain and Intelligence and Department of Biomedical Engineering, Beijing Innovation Center for Future Chip, Center for Brain-Inspired Computing Research, McGovern Institute for Brain Research, Tsinghua University, Beijing, 100084 China
| | - Sen Song
- Tsinghua Laboratory of Brain and Intelligence and Department of Biomedical Engineering, Beijing Innovation Center for Future Chip, Center for Brain-Inspired Computing Research, McGovern Institute for Brain Research, Tsinghua University, Beijing, 100084 China
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Yang Y, Lu J, Zuo Y. Changes of Synaptic Structures Associated with Learning, Memory and Diseases. BRAIN SCIENCE ADVANCES 2019. [DOI: 10.26599/bsa.2018.2018.9050012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Synaptic plasticity is widely believed to be the cellular basis of learning and memory. It is influenced by various factors including development, sensory experiences, and brain disorders. Long-term synaptic plasticity is accompanied by protein synthesis and trafficking, leading to structural changes of the synapse. In this review, we focus on the synaptic structural plasticity, which has mainly been studied with in vivo two-photon laser scanning microscopy. We also discuss how a special type of synapses, the multi-contact synapses (including those formed by multi-synaptic boutons and multi-synaptic spines), are associated with experience and learning.
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Affiliation(s)
- Yang Yang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ju Lu
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064, USA
| | - Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064, USA
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De Niz M, Nacer A, Frischknecht F. Intravital microscopy: Imaging host-parasite interactions in the brain. Cell Microbiol 2019; 21:e13024. [PMID: 30830993 DOI: 10.1111/cmi.13024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 02/14/2019] [Accepted: 02/24/2019] [Indexed: 12/31/2022]
Abstract
Intravital fluorescence microscopy (IVM) is a powerful technique for imaging multiple organs, including the brain of living mice and rats. It enables the direct visualisation of cells in situ providing a real-life view of biological processes that in vitro systems cannot. In addition, to the technological advances in microscopy over the last decade, there have been supporting innovations in data storage and analytical packages that enable the visualisation and analysis of large data sets. Here, we review the advantages and limitations of techniques predominantly used for brain IVM, including thinned skull windows, open skull cortical windows, and a miniaturised optical system based on microendoscopic probes that can be inserted into deep tissues. Further, we explore the relevance of these techniques for the field of parasitology. Several protozoan infections are associated with neurological symptoms including Plasmodium spp., Toxoplasma spp., and Trypanosoma spp. IVM has led to crucial findings on these parasite species, which are discussed in detail in this review.
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Affiliation(s)
- Mariana De Niz
- Institute of Cell Biology, University of Bern, Bern, Switzerland.,Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasglow, UK
| | - Adéla Nacer
- Division of Bacteriology, National Institute for Biological Standards and Control, Medicines and Healthcare products Regulatory Agency, EN63QG, Potters Bar, UK
| | - Friedrich Frischknecht
- Parasitology-Centre for Infectious Diseases, University of Heidelberg Medical School, Heidelberg, Germany
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Fine Control of Sound Frequency Tuning and Frequency Discrimination Acuity by Synaptic Zinc Signaling in Mouse Auditory Cortex. J Neurosci 2018; 39:854-865. [PMID: 30504277 DOI: 10.1523/jneurosci.1339-18.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 10/16/2018] [Accepted: 11/16/2018] [Indexed: 11/21/2022] Open
Abstract
Neurons in the auditory cortex are tuned to specific ranges of sound frequencies. Although the cellular and network mechanisms underlying neuronal sound frequency selectivity are well studied and reflect the interplay of thalamocortical and intracortical excitatory inputs and further refinement by cortical inhibition, the precise synaptic signaling mechanisms remain less understood. To gain further understanding on these mechanisms and their effects on sound-driven behavior, we used in vivo imaging as well as behavioral approaches in awake and behaving female and male mice. We discovered that synaptic zinc, a modulator of neurotransmission and responsiveness to sound, sharpened the sound frequency tuning of principal and parvalbumin-expressing neurons and widened the sound frequency tuning of somatostatin-expressing inhibitory neurons in layer 2/3 of the primary auditory cortex. In the absence of cortical synaptic zinc, mice exhibited reduced acuity for detecting changes in sound frequencies. Together, our results reveal that cell-type-specific effects of zinc contribute to cortical sound frequency tuning and enhance acuity for sound frequency discrimination.SIGNIFICANCE STATEMENT Neuronal tuning to specific features of sensory stimuli is a fundamental property of cortical sensory processing that advantageously supports behavior. Despite the established roles of synaptic thalamocortical and intracortical excitation and inhibition in cortical tuning, the precise synaptic signaling mechanisms remain unknown. Here, we investigated these mechanisms in the mouse auditory cortex. We discovered a previously unknown signaling mechanism linking synaptic zinc signaling with cell-specific cortical tuning and enhancement in sound frequency discrimination acuity. Given the abundance of synaptic zinc in all sensory cortices, this newly discovered interaction between synaptic zinc and cortical tuning can provide a general mechanism for modulating neuronal stimulus specificity and sensory-driven behavior.
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Wei J, Zhong W, Xiao C, Liu Y, Song C, Xiao Z. Selectivity of Monaural Synaptic Inputs Underlying Binaural Auditory Information Integration in the Central Nucleus of Inferior Colliculus. Front Cell Neurosci 2018; 12:303. [PMID: 30337856 PMCID: PMC6180238 DOI: 10.3389/fncel.2018.00303] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 08/21/2018] [Indexed: 11/13/2022] Open
Abstract
Neurons in the central nucleus of the inferior colliculus (ICC) receive ascending inputs from the ipsilateral and contralateral auditory pathway. However, the contributions of excitatory or inhibitory synaptic inputs evoked by ipsilateral and contralateral stimuli to auditory responses of ICC neurons remain unclear. Using in vivo whole-cell voltage-clamp recordings, we investigated excitatory and inhibitory synaptic currents in neurons of the ICC in response to binaural stimulation by performing an intensity-intensity scan. To systematically analyze the contribution of the ipsilateral and contralateral ear, the sound intensity was randomly delivered to each side from 0 dB sound pressure level (SPL) to 70 dB SPL. Although the synaptic responses were dominated by contralateral inputs at weak sound intensities, they could be increased (or decreased) by additional ipsilateral stimulation at higher intensities. Interestingly, the synaptic responses to contralateral acoustic inputs were not linearly superimposed with the ipsilateral ones. By contrast, the responses showed either a contralateral or ipsilateral profile, depending on which one was more dominant. This change occurred at a certain intensity “switch” point. Thus, the binaural auditory responses of the ICC neurons were not simply mediated by the summation of the inputs evoked by ipsilateral and contralateral stimulations. This suggested that the ICC might inherit the acoustic information integrated at the brainstem, causing the selectivity of monaural excitation and inhibition to underlie the neuronal binaural acoustic response.
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Affiliation(s)
- Jinxing Wei
- Key Laboratory of Mental Health of the Ministry of Education, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Wen Zhong
- Key Laboratory of Mental Health of the Ministry of Education, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Cuiyu Xiao
- Key Laboratory of Mental Health of the Ministry of Education, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Yun Liu
- Key Laboratory of Mental Health of the Ministry of Education, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Changbao Song
- Key Laboratory of Mental Health of the Ministry of Education, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Zhongju Xiao
- Key Laboratory of Mental Health of the Ministry of Education, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
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Lohse M, Bajo VM, King AJ. Development, organization and plasticity of auditory circuits: Lessons from a cherished colleague. Eur J Neurosci 2018; 49:990-1004. [PMID: 29804304 PMCID: PMC6519211 DOI: 10.1111/ejn.13979] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/11/2018] [Accepted: 05/23/2018] [Indexed: 12/20/2022]
Abstract
Ray Guillery was a neuroscientist known primarily for his ground-breaking studies on the development of the visual pathways and subsequently on the nature of thalamocortical processing loops. The legacy of his work, however, extends well beyond the visual system. Thanks to Ray Guillery's pioneering anatomical studies, the ferret has become a widely used animal model for investigating the development and plasticity of sensory processing. This includes our own work on the auditory system, where experiments in ferrets have revealed the role of sensory experience during development in shaping the neural circuits responsible for sound localization, as well as the capacity of the mature brain to adapt to changes in inputs resulting from hearing loss. Our research has also built on Ray Guillery's ideas about the possible functions of the massive descending projections that link sensory areas of the cerebral cortex to the thalamus and other subcortical targets, by demonstrating a role for corticothalamic feedback in the perception of complex sounds and for corticollicular projection neurons in learning to accommodate altered auditory spatial cues. Finally, his insights into the organization and functions of transthalamic corticocortical connections have inspired a raft of research, including by our own laboratory, which has attempted to identify how information flows through the thalamus.
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Affiliation(s)
- Michael Lohse
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Victoria M Bajo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Andrew J King
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Babola TA, Li S, Gribizis A, Lee BJ, Issa JB, Wang HC, Crair MC, Bergles DE. Homeostatic Control of Spontaneous Activity in the Developing Auditory System. Neuron 2018; 99:511-524.e5. [PMID: 30077356 DOI: 10.1016/j.neuron.2018.07.004] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 06/01/2018] [Accepted: 06/29/2018] [Indexed: 11/29/2022]
Abstract
Neurons in the developing auditory system exhibit spontaneous bursts of activity before hearing onset. How this intrinsically generated activity influences development remains uncertain, because few mechanistic studies have been performed in vivo. We show using macroscopic calcium imaging in unanesthetized mice that neurons responsible for processing similar frequencies of sound exhibit highly synchronized activity throughout the auditory system during this critical phase of development. Spontaneous activity normally requires synaptic excitation of spiral ganglion neurons (SGNs). Unexpectedly, tonotopic spontaneous activity was preserved in a mouse model of deafness in which glutamate release from hair cells is abolished. SGNs in these mice exhibited enhanced excitability, enabling direct neuronal excitation by supporting cell-induced potassium transients. These results indicate that homeostatic mechanisms maintain spontaneous activity in the pre-hearing period, with significant implications for both circuit development and therapeutic approaches aimed at treating congenital forms of deafness arising through mutations in key sensory transduction components.
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Affiliation(s)
- Travis A Babola
- The Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Sally Li
- The Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Alexandra Gribizis
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Brian J Lee
- The Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - John B Issa
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Han Chin Wang
- The Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Michael C Crair
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Dwight E Bergles
- The Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Otolaryngology Head and Neck Surgery, Johns Hopkins University, Baltimore, MD 21287, USA; Johns Hopkins University Kavli Neuroscience Discovery Institute, Baltimore, MD 21205, USA.
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Auditory midbrain coding of statistical learning that results from discontinuous sensory stimulation. PLoS Biol 2018; 16:e2005114. [PMID: 30048446 PMCID: PMC6065201 DOI: 10.1371/journal.pbio.2005114] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 06/21/2018] [Indexed: 11/19/2022] Open
Abstract
Detecting regular patterns in the environment, a process known as statistical
learning, is essential for survival. Neuronal adaptation is a key mechanism in
the detection of patterns that are continuously repeated across short (seconds
to minutes) temporal windows. Here, we found in mice that a subcortical
structure in the auditory midbrain was sensitive to patterns that were repeated
discontinuously, in a temporally sparse manner, across windows of minutes to
hours. Using a combination of behavioral, electrophysiological, and molecular
approaches, we found changes in neuronal response gain that varied in mechanism
with the degree of sound predictability and resulted in changes in frequency
coding. Analysis of population activity (structural tuning) revealed an increase
in frequency classification accuracy in the context of increased overlap in
responses across frequencies. The increase in accuracy and overlap was
paralleled at the behavioral level in an increase in generalization in the
absence of diminished discrimination. Gain modulation was accompanied by changes
in gene and protein expression, indicative of long-term plasticity.
Physiological changes were largely independent of corticofugal feedback, and no
changes were seen in upstream cochlear nucleus responses, suggesting a key role
of the auditory midbrain in sensory gating. Subsequent behavior demonstrated
learning of predictable and random patterns and their importance in auditory
conditioning. Using longer timescales than previously explored, the combined
data show that the auditory midbrain codes statistical learning of temporally
sparse patterns, a process that is critical for the detection of relevant
stimuli in the constant soundscape that the animal navigates through. Some things are learned simply because they are there and not because they are
relevant at that moment in time. This is particularly true of surrounding
sounds, which we process automatically and continuously, detecting their
repetitive patterns or singularities. Learning about rewards and punishment is
typically attributed to cortical structures in the brain and known to occur over
long time windows. Learning of surrounding regularities, on the other hand, is
attributed to subcortical structures and has been shown to occur in seconds. The
brain can, however, also detect the regularity in sounds that are
discontinuously repeated across intervals of minutes and hours. For example, we
learn to identify people by the sound of their steps through an unconscious
process involving repeated but isolated exposures to the coappearance of sound
and person. Here, we show that a subcortical structure, the auditory midbrain,
can code such temporally spread regularities. Neurons in the auditory midbrain
changed their response pattern in mice that heard a fixed tone whenever they
went into one room in the environment they lived in. Learning of temporally
spread sound patterns can, therefore, occur in subcortical structures.
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Asokan MM, Williamson RS, Hancock KE, Polley DB. Sensory overamplification in layer 5 auditory corticofugal projection neurons following cochlear nerve synaptic damage. Nat Commun 2018; 9:2468. [PMID: 29941910 PMCID: PMC6018400 DOI: 10.1038/s41467-018-04852-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 05/24/2018] [Indexed: 11/09/2022] Open
Abstract
Layer 5 (L5) cortical projection neurons innervate far-ranging brain areas to coordinate integrative sensory processing and adaptive behaviors. Here, we characterize a plasticity in L5 auditory cortex (ACtx) neurons that innervate the inferior colliculus (IC), thalamus, lateral amygdala and striatum. We track daily changes in sound processing using chronic widefield calcium imaging of L5 axon terminals on the dorsal cap of the IC in awake, adult mice. Sound level growth functions at the level of the auditory nerve and corticocollicular axon terminals are both strongly depressed hours after noise-induced damage of cochlear afferent synapses. Corticocollicular response gain rebounded above baseline levels by the following day and remained elevated for several weeks despite a persistent reduction in auditory nerve input. Sustained potentiation of excitatory ACtx projection neurons that innervate multiple limbic and subcortical auditory centers may underlie hyperexcitability and aberrant functional coupling of distributed brain networks in tinnitus and hyperacusis.
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Affiliation(s)
- Meenakshi M Asokan
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA, 02114, USA.
- Division of Medical Sciences, Harvard University, Boston, MA, 02114, USA.
| | - Ross S Williamson
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA, 02114, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02114, USA
| | - Kenneth E Hancock
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA, 02114, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02114, USA
| | - Daniel B Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA, 02114, USA
- Division of Medical Sciences, Harvard University, Boston, MA, 02114, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02114, USA
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Quass GL, Kurt S, Hildebrandt KJ, Kral A. Electrical stimulation of the midbrain excites the auditory cortex asymmetrically. Brain Stimul 2018; 11:1161-1174. [PMID: 29853311 DOI: 10.1016/j.brs.2018.05.009] [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: 02/19/2018] [Revised: 05/09/2018] [Accepted: 05/10/2018] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Auditory midbrain implant users cannot achieve open speech perception and have limited frequency resolution. It remains unclear whether the spread of excitation contributes to this issue and how much it can be compensated by current-focusing, which is an effective approach in cochlear implants. OBJECTIVE The present study examined the spread of excitation in the cortex elicited by electric midbrain stimulation. We further tested whether current-focusing via bipolar and tripolar stimulation is effective with electric midbrain stimulation and whether these modes hold any advantage over monopolar stimulation also in conditions when the stimulation electrodes are in direct contact with the target tissue. METHODS Using penetrating multielectrode arrays, we recorded cortical population responses to single pulse electric midbrain stimulation in 10 ketamine/xylazine anesthetized mice. We compared monopolar, bipolar, and tripolar stimulation configurations with regard to the spread of excitation and the characteristic frequency difference between the stimulation/recording electrodes. RESULTS The cortical responses were distributed asymmetrically around the characteristic frequency of the stimulated midbrain region with a strong activation in regions tuned up to one octave higher. We found no significant differences between monopolar, bipolar, and tripolar stimulation in threshold, evoked firing rate, or dynamic range. CONCLUSION The cortical responses to electric midbrain stimulation are biased towards higher tonotopic frequencies. Current-focusing is not effective in direct contact electrical stimulation. Electrode maps should account for the asymmetrical spread of excitation when fitting auditory midbrain implants by shifting the frequency-bands downward and stimulating as dorsally as possible.
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Affiliation(s)
- Gunnar Lennart Quass
- Institute of AudioNeuroTechnology (VIANNA), Dept. of Experimental Otology, ENT Clinics, Hannover Medical School, 30625 Hannover, Germany; Cluster of Excellence "Hearing4all", Germany.
| | - Simone Kurt
- Institute of AudioNeuroTechnology (VIANNA), Dept. of Experimental Otology, ENT Clinics, Hannover Medical School, 30625 Hannover, Germany; Cluster of Excellence "Hearing4all", Germany
| | - K Jannis Hildebrandt
- Cluster of Excellence "Hearing4all", Germany; Research Center Neurosensory Science, University of Oldenburg, 26111 Oldenburg, Germany
| | - Andrej Kral
- Institute of AudioNeuroTechnology (VIANNA), Dept. of Experimental Otology, ENT Clinics, Hannover Medical School, 30625 Hannover, Germany; Cluster of Excellence "Hearing4all", Germany
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Kuchibhotla K, Bathellier B. Neural encoding of sensory and behavioral complexity in the auditory cortex. Curr Opin Neurobiol 2018; 52:65-71. [PMID: 29709885 DOI: 10.1016/j.conb.2018.04.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 03/01/2018] [Accepted: 04/07/2018] [Indexed: 01/07/2023]
Abstract
Converging evidence now supports the idea that auditory cortex is an important step for the emergence of auditory percepts. Recent studies have extended the list of complex, nonlinear sound features coded by cortical neurons. Moreover, we are beginning to uncover general properties of cortical representations, such as invariance and discreteness, which reflect the structure of auditory perception. Complexity, however, emerges not only through nonlinear shaping of auditory information into perceptual bricks. Behavioral context and task-related information strongly influence cortical encoding of sounds via ascending neuromodulation and descending top-down frontal control. These effects appear to be mediated through local inhibitory networks. Thus, auditory cortex can be seen as a hub linking structured sensory representations with behavioral variables.
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Affiliation(s)
- Kishore Kuchibhotla
- Department of Psychological and Brain Sciences, Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21218, United States; Laboratoire de Neurosciences Cognitives, INSERM U960, École Normale Supérieure - PSL Research University, Paris, France
| | - Brice Bathellier
- Unité de Neuroscience, Information et Complexité (UNIC), FRE 3693, Centre National de la Recherche Scientifique and Paris-Saclay University, Gif-sur-Yvette, 91198, France.
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Panniello M, King AJ, Dahmen JC, Walker KMM. Local and Global Spatial Organization of Interaural Level Difference and Frequency Preferences in Auditory Cortex. Cereb Cortex 2018; 28:350-369. [PMID: 29136122 PMCID: PMC5991210 DOI: 10.1093/cercor/bhx295] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 10/10/2017] [Indexed: 12/16/2022] Open
Abstract
Despite decades of microelectrode recordings, fundamental questions remain about how auditory cortex represents sound-source location. Here, we used in vivo 2-photon calcium imaging to measure the sensitivity of layer II/III neurons in mouse primary auditory cortex (A1) to interaural level differences (ILDs), the principal spatial cue in this species. Although most ILD-sensitive neurons preferred ILDs favoring the contralateral ear, neurons with either midline or ipsilateral preferences were also present. An opponent-channel decoder accurately classified ILDs using the difference in responses between populations of neurons that preferred contralateral-ear-greater and ipsilateral-ear-greater stimuli. We also examined the spatial organization of binaural tuning properties across the imaged neurons with unprecedented resolution. Neurons driven exclusively by contralateral ear stimuli or by binaural stimulation occasionally formed local clusters, but their binaural categories and ILD preferences were not spatially organized on a more global scale. In contrast, the sound frequency preferences of most neurons within local cortical regions fell within a restricted frequency range, and a tonotopic gradient was observed across the cortical surface of individual mice. These results indicate that the representation of ILDs in mouse A1 is comparable to that of most other mammalian species, and appears to lack systematic or consistent spatial order.
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Affiliation(s)
- Mariangela Panniello
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Andrew J King
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Johannes C Dahmen
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Kerry M M Walker
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Blazquez Freches G, Chavarrias C, Shemesh N. BOLD-fMRI in the mouse auditory pathway. Neuroimage 2018; 165:265-277. [DOI: 10.1016/j.neuroimage.2017.10.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 10/09/2017] [Accepted: 10/13/2017] [Indexed: 01/31/2023] Open
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Vasquez-Lopez SA, Weissenberger Y, Lohse M, Keating P, King AJ, Dahmen JC. Thalamic input to auditory cortex is locally heterogeneous but globally tonotopic. eLife 2017; 6:25141. [PMID: 28891466 PMCID: PMC5614559 DOI: 10.7554/elife.25141] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 09/08/2017] [Indexed: 12/24/2022] Open
Abstract
Topographic representation of the receptor surface is a fundamental feature of sensory cortical organization. This is imparted by the thalamus, which relays information from the periphery to the cortex. To better understand the rules governing thalamocortical connectivity and the origin of cortical maps, we used in vivo two-photon calcium imaging to characterize the properties of thalamic axons innervating different layers of mouse auditory cortex. Although tonotopically organized at a global level, we found that the frequency selectivity of individual thalamocortical axons is surprisingly heterogeneous, even in layers 3b/4 of the primary cortical areas, where the thalamic input is dominated by the lemniscal projection. We also show that thalamocortical input to layer 1 includes collaterals from axons innervating layers 3b/4 and is largely in register with the main input targeting those layers. Such locally varied thalamocortical projections may be useful in enabling rapid contextual modulation of cortical frequency representations.
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Affiliation(s)
| | - Yves Weissenberger
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Michael Lohse
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter Keating
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom.,Ear Institute, University College London, London, United Kingdom
| | - Andrew J King
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Johannes C Dahmen
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Tsukano H, Horie M, Ohga S, Takahashi K, Kubota Y, Hishida R, Takebayashi H, Shibuki K. Reconsidering Tonotopic Maps in the Auditory Cortex and Lemniscal Auditory Thalamus in Mice. Front Neural Circuits 2017; 11:14. [PMID: 28293178 PMCID: PMC5330090 DOI: 10.3389/fncir.2017.00014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/20/2017] [Indexed: 11/13/2022] Open
Abstract
The auditory thalamus and auditory cortex (AC) are pivotal structures in the central auditory system. However, the thalamocortical mechanisms of processing sounds are largely unknown. Investigation of this process benefits greatly from the use of mice because the mouse is a powerful animal model in which various experimental techniques, especially genetic tools, can be applied. However, the use of mice has been limited in auditory research, and thus even basic anatomical knowledge of the mouse central auditory system has not been sufficiently collected. Recently, optical imaging combined with morphological analyses has enabled the elucidation of detailed anatomical properties of the mouse auditory system. These techniques have uncovered fine AC maps with multiple frequency-organized regions, each of which receives point-to-point thalamocortical projections from different origins inside the lemniscal auditory thalamus, the ventral division of the medial geniculate body (MGv). This precise anatomy now provides a platform for physiological research. In this mini review article, we summarize these recent achievements that will facilitate physiological investigations in the mouse auditory system.
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Affiliation(s)
- Hiroaki Tsukano
- Department of Neurophysiology, Brain Research Institute, Niigata University Niigata, Japan
| | - Masao Horie
- Division of Neurobiology and Anatomy, Graduate School of Medicine and Dental Sciences, Niigata University Niigata, Japan
| | - Shinpei Ohga
- Department of Neurophysiology, Brain Research Institute, Niigata University Niigata, Japan
| | - Kuniyuki Takahashi
- Division of Otolaryngology, Graduate School of Medicine and Dental Sciences, Niigata University Niigata, Japan
| | - Yamato Kubota
- Division of Otolaryngology, Graduate School of Medicine and Dental Sciences, Niigata University Niigata, Japan
| | - Ryuichi Hishida
- Department of Neurophysiology, Brain Research Institute, Niigata University Niigata, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medicine and Dental Sciences, Niigata University Niigata, Japan
| | - Katsuei Shibuki
- Department of Neurophysiology, Brain Research Institute, Niigata University Niigata, Japan
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Voziyanov V, Kemp BS, Dressel CA, Ponder K, Murray TA. TRIO Platform: A Novel Low Profile In vivo Imaging Support and Restraint System for Mice. Front Neurosci 2016; 10:169. [PMID: 27199633 PMCID: PMC4842766 DOI: 10.3389/fnins.2016.00169] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 04/04/2016] [Indexed: 11/17/2022] Open
Abstract
High resolution, in vivo optical imaging of the mouse brain over time often requires anesthesia, which necessitates maintaining the animal's body temperature and level of anesthesia, as well as securing the head in an optimal, stable position. Controlling each parameter usually requires using multiple systems. Assembling multiple components into the small space on a standard microscope stage can be difficult and some commercially available parts simply do not fit. Furthermore, it is time-consuming to position an animal in the identical position over multiple imaging sessions for longitudinal studies. This is especially true when using an implanted gradient index (GRIN) lens for deep brain imaging. The multiphoton laser beam must be parallel with the shaft of the lens because even a slight tilt of the lens can degrade image quality. In response to these challenges, we have designed a compact, integrated in vivo imaging support system to overcome the problems created by using separate systems during optical imaging in mice. It is a single platform that provides (1) sturdy head fixation, (2) an integrated gas anesthesia mask, and (3) safe warm water heating. This THREE-IN-ONE (TRIO) Platform has a small footprint and a low profile that positions a mouse's head only 20 mm above the microscope stage. This height is about one half to one third the height of most commercially available immobilization devices. We have successfully employed this system, using isoflurane in over 40 imaging sessions with an average of 2 h per session with no leaks or other malfunctions. Due to its smaller size, the TRIO Platform can be used with a wider range of upright microscopes and stages. Most of the components were designed in SOLIDWORKS® and fabricated using a 3D printer. This additive manufacturing approach also readily permits size modifications for creating systems for other small animals.
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Affiliation(s)
- Vladislav Voziyanov
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech UniversityRuston, LA, USA; School of Biological and Health Systems Engineering, Ira A. Fulton School of Engineering, Arizona State UniversityTempe, AZ, USA
| | - Benjamin S Kemp
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University Ruston, LA, USA
| | - Chelsea A Dressel
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University Ruston, LA, USA
| | - Kayla Ponder
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University Ruston, LA, USA
| | - Teresa A Murray
- Integrated Neuroscience and Imaging Lab, Center for Biomedical Engineering and Rehabilitation Sciences, Louisiana Tech University Ruston, LA, USA
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Wallace MM, Harris JA, Brubaker DQ, Klotz CA, Gabriele ML. Graded and discontinuous EphA-ephrinB expression patterns in the developing auditory brainstem. Hear Res 2016; 335:64-75. [PMID: 26906676 DOI: 10.1016/j.heares.2016.02.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Revised: 02/02/2016] [Accepted: 02/18/2016] [Indexed: 01/06/2023]
Abstract
Eph-ephrin interactions guide topographic mapping and pattern formation in a variety of systems. In contrast to other sensory pathways, their precise role in the assembly of central auditory circuits remains poorly understood. The auditory midbrain, or inferior colliculus (IC) is an intriguing structure for exploring guidance of patterned projections as adjacent subdivisions exhibit distinct organizational features. The central nucleus of the IC (CNIC) and deep aspects of its neighboring lateral cortex (LCIC, Layer 3) are tonotopically-organized and receive layered inputs from primarily downstream auditory sources. While less is known about more superficial aspects of the LCIC, its inputs are multimodal, lack a clear tonotopic order, and appear discontinuous, terminating in modular, patch/matrix-like distributions. Here we utilize X-Gal staining approaches in lacZ mutant mice (ephrin-B2, -B3, and EphA4) to reveal EphA-ephrinB expression patterns in the nascent IC during the period of projection shaping that precedes hearing onset. We also report early postnatal protein expression in the cochlear nuclei, the superior olivary complex, the nuclei of the lateral lemniscus, and relevant midline structures. Continuous ephrin-B2 and EphA4 expression gradients exist along frequency axes of the CNIC and LCIC Layer 3. In contrast, more superficial LCIC localization is not graded, but confined to a series of discrete ephrin-B2 and EphA4-positive Layer 2 modules. While heavily expressed in the midline, much of the auditory brainstem is devoid of ephrin-B3, including the CNIC, LCIC Layer 2 modular fields, the dorsal nucleus of the lateral lemniscus (DNLL), as well as much of the superior olivary complex and cochlear nuclei. Ephrin-B3 LCIC expression appears complementary to that of ephrin-B2 and EphA4, with protein most concentrated in presumptive extramodular zones. Described tonotopic gradients and seemingly complementary modular/extramodular patterns suggest Eph-ephrin guidance in establishing juxtaposed continuous and discrete neural maps in the developing IC prior to experience.
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Affiliation(s)
- Matthew M Wallace
- James Madison University, Department of Biology, Harrisonburg, VA 22807, USA
| | - J Aaron Harris
- James Madison University, Department of Biology, Harrisonburg, VA 22807, USA
| | - Donald Q Brubaker
- James Madison University, Department of Biology, Harrisonburg, VA 22807, USA
| | - Caitlyn A Klotz
- James Madison University, Department of Biology, Harrisonburg, VA 22807, USA
| | - Mark L Gabriele
- James Madison University, Department of Biology, Harrisonburg, VA 22807, USA.
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Shen L, Zhao L, Hong B. Frequency-specific adaptation and its underlying circuit model in the auditory midbrain. Front Neural Circuits 2015; 9:55. [PMID: 26483641 PMCID: PMC4589587 DOI: 10.3389/fncir.2015.00055] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 09/16/2015] [Indexed: 11/13/2022] Open
Abstract
Receptive fields of sensory neurons are considered to be dynamic and depend on the stimulus history. In the auditory system, evidence of dynamic frequency-receptive fields has been found following stimulus-specific adaptation (SSA). However, the underlying mechanism and circuitry of SSA have not been fully elucidated. Here, we studied how frequency-receptive fields of neurons in rat inferior colliculus (IC) changed when exposed to a biased tone sequence. Pure tone with one specific frequency (adaptor) was presented markedly more often than others. The adapted tuning was compared with the original tuning measured with an unbiased sequence. We found inhomogeneous changes in frequency tuning in IC, exhibiting a center-surround pattern with respect to the neuron's best frequency. Central adaptors elicited strong suppressive and repulsive changes while flank adaptors induced facilitative and attractive changes. Moreover, we proposed a two-layer model of the underlying network, which not only reproduced the adaptive changes in the receptive fields but also predicted novelty responses to oddball sequences. These results suggest that frequency-specific adaptation in auditory midbrain can be accounted for by an adapted frequency channel and its lateral spreading of adaptation, which shed light on the organization of the underlying circuitry.
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Affiliation(s)
- Li Shen
- Department of Biomedical Engineering, School of Medicine, Tsinghua University Beijing, China
| | - Lingyun Zhao
- Department of Biomedical Engineering, School of Medicine, Tsinghua University Beijing, China
| | - Bo Hong
- Department of Biomedical Engineering, School of Medicine, Tsinghua University Beijing, China
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