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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 DOI: 10.1152/jn.00013.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Clayton KK, Stecyk KS, Guo AA, Chambers AR, Chen K, Hancock KE, Polley DB. Sound elicits stereotyped facial movements that provide a sensitive index of hearing abilities in mice. Curr Biol 2024; 34:1605-1620.e5. [PMID: 38492568 DOI: 10.1016/j.cub.2024.02.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 01/02/2024] [Accepted: 02/23/2024] [Indexed: 03/18/2024]
Abstract
Sound elicits rapid movements of muscles in the face, ears, and eyes that protect the body from injury and trigger brain-wide internal state changes. Here, we performed quantitative facial videography from mice resting atop a piezoelectric force plate and observed that broadband sounds elicited rapid and stereotyped facial twitches. Facial motion energy (FME) adjacent to the whisker array was 30 dB more sensitive than the acoustic startle reflex and offered greater inter-trial and inter-animal reliability than sound-evoked pupil dilations or movement of other facial and body regions. FME tracked the low-frequency envelope of broadband sounds, providing a means to study behavioral discrimination of complex auditory stimuli, such as speech phonemes in noise. Approximately 25% of layer 5-6 units in the auditory cortex (ACtx) exhibited firing rate changes during facial movements. However, FME facilitation during ACtx photoinhibition indicated that sound-evoked facial movements were mediated by a midbrain pathway and modulated by descending corticofugal input. FME and auditory brainstem response (ABR) thresholds were closely aligned after noise-induced sensorineural hearing loss, yet FME growth slopes were disproportionately steep at spared frequencies, reflecting a central plasticity that matched commensurate changes in ABR wave 4. Sound-evoked facial movements were also hypersensitive in Ptchd1 knockout mice, highlighting the use of FME for identifying sensory hyper-reactivity phenotypes after adult-onset hyperacusis and inherited deficiencies in autism risk genes. These findings present a sensitive and integrative measure of hearing while also highlighting that even low-intensity broadband sounds can elicit a complex mixture of auditory, motor, and reafferent somatosensory neural activity.
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Affiliation(s)
- Kameron K Clayton
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02114, USA.
| | - Kamryn S Stecyk
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA
| | - Anna A Guo
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA
| | - Anna R Chambers
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02114, USA
| | - Ke Chen
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02114, USA
| | - Kenneth E Hancock
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02114, USA
| | - Daniel B Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02114, USA
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Liu M, Gao Y, Xin F, Hu Y, Wang T, Xie F, Shao C, Li T, Wang N, Yuan K. Parvalbumin and Somatostatin: Biomarkers for Two Parallel Tectothalamic Pathways in the Auditory Midbrain. J Neurosci 2024; 44:e1655232024. [PMID: 38326037 PMCID: PMC10919325 DOI: 10.1523/jneurosci.1655-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 01/15/2024] [Accepted: 01/20/2024] [Indexed: 02/09/2024] Open
Abstract
The inferior colliculus (IC) represents a crucial relay station in the auditory pathway, located in the midbrain's tectum and primarily projecting to the thalamus. Despite the identification of distinct cell classes based on various biomarkers in the IC, their specific contributions to the organization of auditory tectothalamic pathways have remained poorly understood. In this study, we demonstrate that IC neurons expressing parvalbumin (ICPV+) or somatostatin (ICSOM+) represent two minimally overlapping cell classes throughout the three IC subdivisions in mice of both sexes. Strikingly, regardless of their location within the IC, these neurons predominantly project to the primary and secondary auditory thalamic nuclei, respectively. Cell class-specific input tracing suggested that ICPV+ neurons primarily receive auditory inputs, whereas ICSOM+ neurons receive significantly more inputs from the periaqueductal gray and the superior colliculus (SC), which are sensorimotor regions critically involved in innate behaviors. Furthermore, ICPV+ neurons exhibit significant heterogeneity in both intrinsic electrophysiological properties and presynaptic terminal size compared with ICSOM+ neurons. Notably, approximately one-quarter of ICPV+ neurons are inhibitory neurons, whereas all ICSOM+ neurons are excitatory neurons. Collectively, our findings suggest that parvalbumin and somatostatin expression in the IC can serve as biomarkers for two functionally distinct, parallel tectothalamic pathways. This discovery suggests an alternative way to define tectothalamic pathways and highlights the potential usefulness of Cre mice in understanding the multifaceted roles of the IC at the circuit level.
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Affiliation(s)
- Mengting Liu
- Department of Otorhinolaryngology Head and Neck Surgery, First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, China
| | - Yixiao Gao
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Fengyuan Xin
- School of Biomedical Engineering, Tsinghua University, Beijing 100084, China
| | - Ying Hu
- Zhili College, Tsinghua University, Beijing 100084, China
| | - Tao Wang
- Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Fenghua Xie
- School of Biomedical Engineering, Tsinghua University, Beijing 100084, China
- Tsinghua Laboratory of Brain and Intelligence, Tsinghua University, Beijing 100084, China
| | - Chengjun Shao
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Tianyu Li
- School of Biomedical Engineering, Tsinghua University, Beijing 100084, China
| | - Ningyu Wang
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China
| | - Kexin Yuan
- School of Biomedical Engineering, Tsinghua University, Beijing 100084, China
- Tsinghua Laboratory of Brain and Intelligence, Tsinghua University, Beijing 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing 10084, China
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Farhadi A, Jennings SG, Strickland EA, Carney LH. Subcortical auditory model including efferent dynamic gain control with inputs from cochlear nucleus and inferior colliculus. J Acoust Soc Am 2023; 154:3644-3659. [PMID: 38051523 PMCID: PMC10836963 DOI: 10.1121/10.0022578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 10/21/2023] [Accepted: 11/13/2023] [Indexed: 12/07/2023]
Abstract
An auditory model has been developed with a time-varying, gain-control signal based on the physiology of the efferent system and subcortical neural pathways. The medial olivocochlear (MOC) efferent stage of the model receives excitatory projections from fluctuation-sensitive model neurons of the inferior colliculus (IC) and wide-dynamic-range model neurons of the cochlear nucleus. The response of the model MOC stage dynamically controls cochlear gain via simulated outer hair cells. In response to amplitude-modulated (AM) noise, firing rates of most IC neurons with band-enhanced modulation transfer functions in awake rabbits increase over a time course consistent with the dynamics of the MOC efferent feedback. These changes in the rates of IC neurons in awake rabbits were employed to adjust the parameters of the efferent stage of the proposed model. Responses of the proposed model to AM noise were able to simulate the increasing IC rate over time, whereas the model without the efferent system did not show this trend. The proposed model with efferent gain control provides a powerful tool for testing hypotheses, shedding insight on mechanisms in hearing, specifically those involving the efferent system.
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Affiliation(s)
- Afagh Farhadi
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14642, USA
| | - Skyler G Jennings
- Department of Communication Sciences and Disorders, University of Utah, Salt Lake City, Utah 84112, USA
| | - Elizabeth A Strickland
- Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, Indiana 47907, USA
| | - Laurel H Carney
- Department of Biomedical Engineering, University of Rochester, Rochester, New York 14642, USA
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Silveira MA, Drotos AC, Pirrone TM, Versalle TS, Bock A, Roberts MT. Neuropeptide Y Signaling Regulates Recurrent Excitation in the Auditory Midbrain. J Neurosci 2023; 43:7626-7641. [PMID: 37704372 PMCID: PMC10634549 DOI: 10.1523/jneurosci.0900-23.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 09/05/2023] [Accepted: 09/06/2023] [Indexed: 09/15/2023] Open
Abstract
Neuropeptides play key roles in shaping the organization and function of neuronal circuits. In the inferior colliculus (IC), which is in the auditory midbrain, Neuropeptide Y (NPY) is expressed by a class of GABAergic neurons that project locally and outside the IC. Most neurons in the IC have local axon collaterals; however, the organization and function of local circuits in the IC remain unknown. We previously found that excitatory neurons in the IC can express the NPY Y1 receptor (Y1R+) and application of the Y1R agonist, [Leu31, Pro34]-NPY (LP-NPY), decreases the excitability of Y1R+ neurons. As NPY signaling regulates recurrent excitation in other brain regions, we hypothesized that Y1R+ neurons form interconnected local circuits in the IC and that NPY decreases the strength of recurrent excitation in these circuits. To test this hypothesis, we used optogenetics to activate Y1R+ neurons in mice of both sexes while recording from other neurons in the ipsilateral IC. We found that nearly 80% of glutamatergic IC neurons express the Y1 receptor, providing extensive opportunities for NPY signaling to regulate local circuits. Additionally, Y1R+ neuron synapses exhibited modest short-term synaptic plasticity, suggesting that local excitatory circuits maintain their influence over computations during sustained stimuli. We further found that application of LP-NPY decreased recurrent excitation in the IC, suggesting that NPY signaling strongly regulates local circuit function in the auditory midbrain. Our findings show that Y1R+ excitatory neurons form interconnected local circuits in the IC, and their influence over local circuits is regulated by NPY signaling.SIGNIFICANCE STATEMENT Local networks play fundamental roles in shaping neuronal computations in the brain. The IC, localized in the auditory midbrain, plays an essential role in sound processing, but the organization of local circuits in the IC is largely unknown. Here, we show that IC neurons that express the Neuropeptide Y1 receptor (Y1R+ neurons) make up most of the excitatory neurons in the IC and form interconnected local circuits. Additionally, we found that NPY, which is a powerful neuromodulator known to shape neuronal activity in other brain regions, decreases the extensive recurrent excitation mediated by Y1R+ neurons in local IC circuits. Thus, our results suggest that local NPY signaling is a key regulator of auditory computations in the IC.
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Affiliation(s)
- Marina A Silveira
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan 48109
| | - Audrey C Drotos
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan 48109
| | - Trinity M Pirrone
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan 48109
- Macalester College, St. Paul, Minnesota 55105
| | - Trevor S Versalle
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan 48109
| | - Amanda Bock
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan 48109
| | - Michael T Roberts
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan 48109
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109
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