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Ikeda K, Campbell TA. Binaural interaction in human auditory brainstem and middle-latency responses affected by sound frequency band, lateralization predictability, and attended modality. Hear Res 2024; 452:109089. [PMID: 39137721 DOI: 10.1016/j.heares.2024.109089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 07/11/2024] [Accepted: 07/16/2024] [Indexed: 08/15/2024]
Abstract
The binaural interaction component (BIC) of the auditory evoked potential is the difference between the waveforms of the binaural response and the sum of left and right monaural responses. This investigation examined BICs of the auditory brainstem (ABR) and middle-latency (MLR) responses concerning three objectives: 1) the level of the auditory system at which low-frequency dominance in BIC amplitudes begins when the binaural temporal fine structure is more influential with lower- than higher-frequency content; 2) how BICs vary as a function of frequency and lateralization predictability, as could relate to the improved lateralization of high-frequency sounds; 3) how attention affects BICs. Sixteen right-handed participants were presented with either low-passed (< 1000 Hz) or high-passed (> 2000 Hz) clicks at 30 dB SL with a 38 dB (A) masking noise, at a stimulus onset asynchrony of 180 ms. Further, this repeated-measures design manipulated stimulus presentation (binaural, left monaural, right monaural), lateralization predictability (unpredictable, predictable), and attended modality (either auditory or visual). For the objectives, respectively, the results were: 1) whereas low-frequency dominance in BIC amplitudes began during, and continued after, the Na-BIC, binaural (center) as well as summed monaural (left and right) amplitudes revealed low-frequency dominance only after the Na wave; 2) with a predictable position that was fixed, no BIC exhibited equivalent amplitudes between low- and high-passed clicks; 3) whether clicks were low- or high-passed, selective attention affected the ABR-BIC yet not MLR-BICs. These findings indicate that low-frequency dominance in lateralization begins at the Na latency, being independent of the efferent cortico-collicular pathway's influence.
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Affiliation(s)
- Kazunari Ikeda
- Laboratory of Cognitive Psychophysiology, Tokyo Gakugei University, Koganei, Tokyo 184-8501, Japan.
| | - Tom A Campbell
- Faculty of Information Technology and Communication Sciences, Tampere University, 33720 Tampere, Finland
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2
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Noftz WA, Echols EE, Beebe NL, Mellott JG, Schofield BR. Differential cholinergic innervation of lemniscal versus non-lemniscal regions of the inferior colliculus. J Chem Neuroanat 2024; 139:102443. [PMID: 38914378 DOI: 10.1016/j.jchemneu.2024.102443] [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: 05/16/2024] [Revised: 06/12/2024] [Accepted: 06/17/2024] [Indexed: 06/26/2024]
Abstract
The inferior colliculus (IC), a midbrain hub for integration of auditory information, receives dense cholinergic input that could modulate nearly all aspects of hearing. A key step in understanding cholinergic modulation is to identify the source(s) and termination patterns of cholinergic input. These issues have not been addressed for the IC in mice, an increasingly important model for study of hearing. We examined cholinergic inputs to the IC in adult male and female mice. We used retrograde tracing and immunochemistry to identify three sources of cholinergic innervation of the mouse IC: the pedunculopontine tegmental nucleus (PPT), the laterodorsal tegmental nucleus (LDT) and the lateral paragigantocellular nucleus (LPGi). We then used Cre-dependent labeling of cholinergic neurons in normal-hearing ChAT-Cre mice to selectively label the cholinergic projections to the IC from each of the cholinergic sources. Labeling of cholinergic projections from the PPT and LDT revealed cholinergic axons and boutons terminating throughout the IC, with the ipsilateral projection being denser. Electron microscopic examination showed that these cholinergic axons can form traditional synaptic junctions with IC neurons. In separate experiments, selective labeling of cholinergic projections from the LPGi revealed bilateral projections to the IC. The LPGi axons exhibited relatively equal densities on ipsilateral and contralateral sides, but on both sides the terminations were largely restricted to the non-lemniscal regions of the IC (i.e., the dorsal cortex, lateral cortex and intercollicular tegmentum). We conclude first that cholinergic axons can form traditional synapses in the IC. In addition, lemniscal and non-lemniscal regions of the IC receive different patterns of cholinergic innervation. The lemniscal IC (IC central nucleus) is innervated by cholinergic neurons in the PPT and the LDT whereas the non-lemniscal "shell" areas of the IC are innervated by the PPT and LDT and by cholinergic neurons in the LPGi. DATA AVAILABILITY: Data will be made available on request.
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Affiliation(s)
- William A Noftz
- Department of Anatomy and Neurobiology, University Hospitals Hearing Research Center at NEOMED, Northeast Ohio Medical University, Rootstown, OH 44272, USA
| | - Emily E Echols
- Department of Biology, University of Akron, Akron, OH 44325, USA
| | - Nichole L Beebe
- Department of Anatomy and Neurobiology, University Hospitals Hearing Research Center at NEOMED, Northeast Ohio Medical University, Rootstown, OH 44272, USA
| | - Jeffrey G Mellott
- Department of Anatomy and Neurobiology, University Hospitals Hearing Research Center at NEOMED, Northeast Ohio Medical University, Rootstown, OH 44272, USA
| | - Brett R Schofield
- Department of Anatomy and Neurobiology, University Hospitals Hearing Research Center at NEOMED, Northeast Ohio Medical University, Rootstown, OH 44272, USA.
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3
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Carbajal GV, Casado-Román L, Malmierca MS. Two Prediction Error Systems in the Nonlemniscal Inferior Colliculus: "Spectral" and "Nonspectral". J Neurosci 2024; 44:e1420232024. [PMID: 38627089 PMCID: PMC11154860 DOI: 10.1523/jneurosci.1420-23.2024] [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: 07/27/2023] [Revised: 04/03/2024] [Accepted: 04/10/2024] [Indexed: 06/07/2024] Open
Abstract
According to the predictive processing framework, perception emerges from the reciprocal exchange of predictions and prediction errors (PEs) between hierarchically organized neural circuits. The nonlemniscal division of the inferior colliculus (IC) is the earliest source of auditory PE signals, but their neuronal generators, properties, and functional relevance have remained mostly undefined. We recorded single-unit mismatch responses to auditory oddball stimulation at different intensities, together with activity evoked by two sequences of alternating tones to control frequency-specific effects. Our results reveal a differential treatment of the unpredictable "many-standards" control and the predictable "cascade" control by lemniscal and nonlemniscal IC neurons that is not present in the auditory thalamus or cortex. Furthermore, we found that frequency response areas of nonlemniscal IC neurons reflect their role in subcortical predictive processing, distinguishing three hierarchical levels: (1) nonlemniscal neurons with sharply tuned receptive fields exhibit mild repetition suppression without signaling PEs, thereby constituting the input level of the local predictive processing circuitry. (2) Neurons with broadly tuned receptive fields form the main, "spectral" PE signaling system, which provides dynamic gain compensation to near-threshold unexpected sounds. This early enhancement of saliency reliant on spectral features was not observed in the auditory thalamus or cortex. (3) Untuned neurons form an accessory, "nonspectral" PE signaling system, which reports all surprising auditory deviances in a robust and consistent manner, resembling nonlemniscal neurons in the auditory cortex. These nonlemniscal IC neurons show unstructured and unstable receptive fields that could result from inhibitory input controlled by corticofugal projections conveying top-down predictions.
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Affiliation(s)
- Guillermo V Carbajal
- Cognitive and Auditory Neuroscience Laboratory (CANELAB), Institute of Neuroscience of Castilla y León (INCYL), Salamanca 37007, Spain
- Institute for Biomedical Research of Salamanca (IBSAL), Salamanca 37007, Spain
| | - Lorena Casado-Román
- Cognitive and Auditory Neuroscience Laboratory (CANELAB), Institute of Neuroscience of Castilla y León (INCYL), Salamanca 37007, Spain
- Institute for Biomedical Research of Salamanca (IBSAL), Salamanca 37007, Spain
| | - Manuel S Malmierca
- Cognitive and Auditory Neuroscience Laboratory (CANELAB), Institute of Neuroscience of Castilla y León (INCYL), Salamanca 37007, Spain
- Institute for Biomedical Research of Salamanca (IBSAL), Salamanca 37007, Spain
- Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca, Salamanca 37007, Spain
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Zhu Y, Li C, Hendry C, Glass J, Canseco-Gonzalez E, Pitts MA, Dykstra AR. Isolating Neural Signatures of Conscious Speech Perception with a No-Report Sine-Wave Speech Paradigm. J Neurosci 2024; 44:e0145232023. [PMID: 38191569 PMCID: PMC10883607 DOI: 10.1523/jneurosci.0145-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 11/21/2023] [Accepted: 12/21/2023] [Indexed: 01/10/2024] Open
Abstract
Identifying neural correlates of conscious perception is a fundamental endeavor of cognitive neuroscience. Most studies so far have focused on visual awareness along with trial-by-trial reports of task-relevant stimuli, which can confound neural measures of perceptual awareness with postperceptual processing. Here, we used a three-phase sine-wave speech paradigm that dissociated between conscious speech perception and task relevance while recording EEG in humans of both sexes. Compared with tokens perceived as noise, physically identical sine-wave speech tokens that were perceived as speech elicited a left-lateralized, near-vertex negativity, which we interpret as a phonological version of a perceptual awareness negativity. This response appeared between 200 and 300 ms after token onset and was not present for frequency-flipped control tokens that were never perceived as speech. In contrast, the P3b elicited by task-irrelevant tokens did not significantly differ when the tokens were perceived as speech versus noise and was only enhanced for tokens that were both perceived as speech and relevant to the task. Our results extend the findings from previous studies on visual awareness and speech perception and suggest that correlates of conscious perception, across types of conscious content, are most likely to be found in midlatency negative-going brain responses in content-specific sensory areas.
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Affiliation(s)
- Yunkai Zhu
- Department of Biomedical Engineering, University of Miami, Coral Gables, Florida 33143
| | - Charlotte Li
- Department of Psychology, Reed College, Portland, Oregon 97202
| | - Camille Hendry
- Department of Psychology, Reed College, Portland, Oregon 97202
| | - James Glass
- Department of Psychology, Reed College, Portland, Oregon 97202
| | | | - Michael A Pitts
- Department of Psychology, Reed College, Portland, Oregon 97202
| | - Andrew R Dykstra
- Department of Biomedical Engineering, University of Miami, Coral Gables, Florida 33143
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Hood KE, Hurley LM. Listening to your partner: serotonin increases male responsiveness to female vocal signals in mice. Front Hum Neurosci 2024; 17:1304653. [PMID: 38328678 PMCID: PMC10847236 DOI: 10.3389/fnhum.2023.1304653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 12/28/2023] [Indexed: 02/09/2024] Open
Abstract
The context surrounding vocal communication can have a strong influence on how vocal signals are perceived. The serotonergic system is well-positioned for modulating the perception of communication signals according to context, because serotonergic neurons are responsive to social context, influence social behavior, and innervate auditory regions. Animals like lab mice can be excellent models for exploring how serotonin affects the primary neural systems involved in vocal perception, including within central auditory regions like the inferior colliculus (IC). Within the IC, serotonergic activity reflects not only the presence of a conspecific, but also the valence of a given social interaction. To assess whether serotonin can influence the perception of vocal signals in male mice, we manipulated serotonin systemically with an injection of its precursor 5-HTP, and locally in the IC with an infusion of fenfluramine, a serotonin reuptake blocker. Mice then participated in a behavioral assay in which males suppress their ultrasonic vocalizations (USVs) in response to the playback of female broadband vocalizations (BBVs), used in defensive aggression by females when interacting with males. Both 5-HTP and fenfluramine increased the suppression of USVs during BBV playback relative to controls. 5-HTP additionally decreased the baseline production of a specific type of USV and male investigation, but neither drug treatment strongly affected male digging or grooming. These findings show that serotonin modifies behavioral responses to vocal signals in mice, in part by acting in auditory brain regions, and suggest that mouse vocal behavior can serve as a useful model for exploring the mechanisms of context in human communication.
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Affiliation(s)
- Kayleigh E. Hood
- Hurley Lab, Department of Biology, Indiana University, Bloomington, IN, United States
- Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN, United States
| | - Laura M. Hurley
- Hurley Lab, Department of Biology, Indiana University, Bloomington, IN, United States
- Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN, United States
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Graham G, Chimenti MS, Knudtson KL, Grenard DN, Co L, Sumner M, Tchou T, Bieszczad KM. Learning induces unique transcriptional landscapes in the auditory cortex. Hear Res 2023; 438:108878. [PMID: 37659220 PMCID: PMC10529106 DOI: 10.1016/j.heares.2023.108878] [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: 04/03/2023] [Revised: 08/11/2023] [Accepted: 08/18/2023] [Indexed: 09/04/2023]
Abstract
Learning can induce neurophysiological plasticity in the auditory cortex at multiple timescales. Lasting changes to auditory cortical function that persist over days, weeks, or even a lifetime, require learning to induce de novo gene expression. Indeed, transcription is the molecular determinant for long-term memories to form with a lasting impact on sound-related behavior. However, auditory cortical genes that support auditory learning, memory, and acquired sound-specific behavior are largely unknown. Using an animal model of adult, male Sprague-Dawley rats, this report is the first to identify genome-wide changes in learning-induced gene expression within the auditory cortex that may underlie long-lasting discriminative memory formation of acoustic frequency cues. Auditory cortical samples were collected from animals in the initial learning phase of a two-tone discrimination sound-reward task known to induce sound-specific neurophysiological and behavioral effects. Bioinformatic analyses on gene enrichment profiles from bulk RNA sequencing identified cholinergic synapse (KEGG rno04725), extra-cellular matrix receptor interaction (KEGG rno04512), and neuroactive receptor interaction (KEGG rno04080) among the top biological pathways are likely to be important for auditory discrimination learning. The findings characterize candidate effectors underlying the early stages of changes in cortical and behavioral function to ultimately support the formation of long-term discriminative auditory memory in the adult brain. The molecules and mechanisms identified are potential therapeutic targets to facilitate experiences that induce long-lasting changes to sound-specific auditory function in adulthood and prime for future gene-targeted investigations.
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Affiliation(s)
- G Graham
- Neuroscience Graduate Program, Rutgers Univ., Piscataway, NJ, USA; Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ, USA
| | - M S Chimenti
- Iowa Institute of Human Genetics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - K L Knudtson
- Iowa Institute of Human Genetics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - D N Grenard
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ, USA
| | - L Co
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ, USA
| | - M Sumner
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ, USA
| | - T Tchou
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ, USA
| | - K M Bieszczad
- Neuroscience Graduate Program, Rutgers Univ., Piscataway, NJ, USA; Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ, USA; Rutgers Center for Cognitive Science, Rutgers Univ., Piscataway, NJ, USA; Dept. of Otolaryngology-Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA.
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7
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Gómez-Martínez M, Rincón H, Gómez-Álvarez M, Gómez-Nieto R, Saldaña E. The nuclei of the lateral lemniscus: unexpected players in the descending auditory pathway. Front Neuroanat 2023; 17:1242245. [PMID: 37621862 PMCID: PMC10445163 DOI: 10.3389/fnana.2023.1242245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 07/10/2023] [Indexed: 08/26/2023] Open
Abstract
Introduction In the mammalian auditory pathway, the nuclei of the lateral lemniscus (NLL) are thought to be exclusively involved in the bottom-up transmission of auditory information. However, our repeated observation of numerous NLL neurons labeled after injection of retrograde tracers into the superior olivary complex (SOC) led us to systematically investigate with retrograde tracers the descending projections from the NLL to the SOC of the rat. Methods We performed large injections of FluoroGold into the SOC to determine NLL contributions to descending projections, and focal injections of biotinylated dextran amine (BDA) to pinpoint the specific nuclei of the SOC innervated by each NLL. Results The SOC is innervated by thousands of neurons distributed across four nuclei or regions associated with the lateral lemniscus: the ipsilateral ventral and intermediate nuclei of the lateral lemniscus (VNLL and INLL); the medial paralemniscal region (PL) of both sides; and the ipsilateral semilunar nucleus (SLN), a previously unrecognized nucleus that wraps around the INLL dorsally, medially, and caudally and consists of small, flat neurons. In some experiments, at least 30% of neurons in the VNLL and INLL were retrogradely labeled. All nuclei of the SOC, except the medial and lateral superior olives, are innervated by abundant lemniscal neurons, and each SOC nucleus receives a unique combination of lemniscal inputs. The primary target of the projections from the VNLL is the ventral nucleus of the trapezoid body (VNTB), followed by the superior paraolivary nucleus (SPON), and the medial nucleus of the trapezoid body (MNTB). The INLL selectively innervates the VNTB. The PL innervates dorsal periolivary regions bilaterally. The SLN preferentially innervates the MNTB and may provide the first identified non-calyceal excitatory input to MNTB neurons. Discussion Our novel findings have strong implications for understanding acoustic information processing in the initial stages of the auditory pathway. Based on the proportion of lemniscal neurons involved in all the projections described, the NLL should be considered major players in the descending auditory pathway.
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Affiliation(s)
- Mario Gómez-Martínez
- Neuroscience Institute of Castilla y León, University of Salamanca, Salamanca, Spain
- Department of Cell Biology and Pathology, Medical School, University of Salamanca, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, Salamanca, Spain
| | - Héctor Rincón
- Neuroscience Institute of Castilla y León, University of Salamanca, Salamanca, Spain
- Department of Cell Biology and Pathology, Medical School, University of Salamanca, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, Salamanca, Spain
| | - Marcelo Gómez-Álvarez
- Neuroscience Institute of Castilla y León, University of Salamanca, Salamanca, Spain
- Department of Cell Biology and Pathology, Medical School, University of Salamanca, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, Salamanca, Spain
| | - Ricardo Gómez-Nieto
- Neuroscience Institute of Castilla y León, University of Salamanca, Salamanca, Spain
- Department of Cell Biology and Pathology, Medical School, University of Salamanca, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, Salamanca, Spain
| | - Enrique Saldaña
- Neuroscience Institute of Castilla y León, University of Salamanca, Salamanca, Spain
- Department of Cell Biology and Pathology, Medical School, University of Salamanca, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, Salamanca, Spain
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Graham G, Chimenti MS, Knudtson KL, Grenard DN, Co L, Sumner M, Tchou T, Bieszczad KM. Learning induces unique transcriptional landscapes in the auditory cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.15.536914. [PMID: 37090563 PMCID: PMC10120736 DOI: 10.1101/2023.04.15.536914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Learning can induce neurophysiological plasticity in the auditory cortex at multiple timescales. Lasting changes to auditory cortical function that persist over days, weeks, or even a lifetime, require learning to induce de novo gene expression. Indeed, transcription is the molecular determinant for long-term memories to form with a lasting impact on sound-related behavior. However, auditory cortical genes that support auditory learning, memory, and acquired sound-specific behavior are largely unknown. This report is the first to identify in young adult male rats (Sprague-Dawley) genome-wide changes in learning-induced gene expression within the auditory cortex that may underlie the formation of long-lasting discriminative memory for acoustic frequency cues. Auditory cortical samples were collected from animals in the initial learning phase of a two-tone discrimination sound-reward task known to induce sound-specific neurophysiological and behavioral effects (e.g., Shang et al., 2019). Bioinformatic analyses on gene enrichment profiles from bulk RNA sequencing identified cholinergic synapse (KEGG 04725), extra-cellular matrix receptor interaction (KEGG 04512) , and neuroactive ligand-receptor interaction (KEGG 04080) as top biological pathways for auditory discrimination learning. The findings characterize key candidate effectors underlying changes in cortical function that support the initial formation of long-term discriminative auditory memory in the adult brain. The molecules and mechanisms identified are potential therapeutic targets to facilitate lasting changes to sound-specific auditory function in adulthood and prime for future gene-targeted investigations.
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Affiliation(s)
- G Graham
- Neuroscience Graduate Program, Rutgers Univ., Piscataway, NJ
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ
| | - M S Chimenti
- Iowa Institute of Human Genetics, Univ. of Iowa Carver College of Medicine, Iowa City, IA
| | - K L Knudtson
- Iowa Institute of Human Genetics, Univ. of Iowa Carver College of Medicine, Iowa City, IA
| | - D N Grenard
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ
| | - L Co
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ
| | - M Sumner
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ
| | - T Tchou
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ
| | - K M Bieszczad
- Neuroscience Graduate Program, Rutgers Univ., Piscataway, NJ
- Behavioral and Systems Neuroscience, Dept. of Psychology, Rutgers Univ., Piscataway, NJ
- Rutgers Center for Cognitive Science, Rutgers Univ., Piscataway, NJ
- Dept. of Otolaryngology-Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ
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Ghimire M, Cai R, Ling L, Brownell KA, Hackett TA, Llano DA, Caspary DM. Increased pyramidal and VIP neuronal excitability in rat primary auditory cortex directly correlates with tinnitus behaviour. J Physiol 2023; 601:2493-2511. [PMID: 37119035 PMCID: PMC10330441 DOI: 10.1113/jp284675] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 04/25/2023] [Indexed: 04/30/2023] Open
Abstract
Tinnitus affects roughly 15%-20% of the population while severely impacting 10% of those afflicted. Tinnitus pathology is multifactorial, generally initiated by damage to the auditory periphery, resulting in a cascade of maladaptive plastic changes at multiple levels of the central auditory neuraxis as well as limbic and non-auditory cortical centres. Using a well-established condition-suppression model of tinnitus, we measured tinnitus-related changes in the microcircuits of excitatory/inhibitory neurons onto layer 5 pyramidal neurons (PNs), as well as changes in the excitability of vasoactive intestinal peptide (VIP) neurons in primary auditory cortex (A1). Patch-clamp recordings from PNs in A1 slices showed tinnitus-related increases in spontaneous excitatory postsynaptic currents (sEPSCs) and decreases in spontaneous inhibitory postsynaptic currents (sIPSCs). Both measures could be correlated to the rat's behavioural evidence of tinnitus. Tinnitus-related changes in PN excitability were independent of changes in A1 excitatory or inhibitory cell numbers. VIP neurons, part of an A1 local circuit that can control the excitation of layer 5 PNs via disinhibitory mechanisms, showed significant tinnitus-related increases in excitability that directly correlated with the rat's behavioural tinnitus score. That PN and VIP changes directly correlated to tinnitus behaviour suggests an important role in A1 tinnitus pathology. Tinnitus-related A1 changes were similar to findings in studies of neuropathic pain in somatosensory cortex suggesting a common pathology of these troublesome perceptual impairments. Improved understanding between excitatory, inhibitory and disinhibitory sensory cortical circuits can serve as a model for testing therapeutic approaches to the treatment of tinnitus and chronic pain. KEY POINTS: We identified tinnitus-related changes in synaptic function of specific neuronal subtypes in a reliable animal model of tinnitus. The findings show direct and indirect tinnitus-related losses of normal inhibitory function at A1 layer 5 pyramidal cells, and increased VIP excitability. The findings are similar to what has been shown for neuropathic pain suggesting that restoring normal inhibitory function at synaptic inputs onto A1 pyramidal neurons (PNs) could conceptually reduce tinnitus discomfort.
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Affiliation(s)
- Madan Ghimire
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62702
| | - Rui Cai
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62702
| | - Lynne Ling
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62702
| | - Kevin A. Brownell
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62702
| | - Troy A. Hackett
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - Daniel A. Llano
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Donald M. Caspary
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62702
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Carter JA, Bidelman GM. Perceptual warping exposes categorical representations for speech in human brainstem responses. Neuroimage 2023; 269:119899. [PMID: 36720437 PMCID: PMC9992300 DOI: 10.1016/j.neuroimage.2023.119899] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 01/17/2023] [Accepted: 01/22/2023] [Indexed: 01/30/2023] Open
Abstract
The brain transforms continuous acoustic events into discrete category representations to downsample the speech signal for our perceptual-cognitive systems. Such phonetic categories are highly malleable, and their percepts can change depending on surrounding stimulus context. Previous work suggests these acoustic-phonetic mapping and perceptual warping of speech emerge in the brain no earlier than auditory cortex. Here, we examined whether these auditory-category phenomena inherent to speech perception occur even earlier in the human brain, at the level of auditory brainstem. We recorded speech-evoked frequency following responses (FFRs) during a task designed to induce more/less warping of listeners' perceptual categories depending on stimulus presentation order of a speech continuum (random, forward, backward directions). We used a novel clustered stimulus paradigm to rapidly record the high trial counts needed for FFRs concurrent with active behavioral tasks. We found serial stimulus order caused perceptual shifts (hysteresis) near listeners' category boundary confirming identical speech tokens are perceived differentially depending on stimulus context. Critically, we further show neural FFRs during active (but not passive) listening are enhanced for prototypical vs. category-ambiguous tokens and are biased in the direction of listeners' phonetic label even for acoustically-identical speech stimuli. These findings were not observed in the stimulus acoustics nor model FFR responses generated via a computational model of cochlear and auditory nerve transduction, confirming a central origin to the effects. Our data reveal FFRs carry category-level information and suggest top-down processing actively shapes the neural encoding and categorization of speech at subcortical levels. These findings suggest the acoustic-phonetic mapping and perceptual warping in speech perception occur surprisingly early along the auditory neuroaxis, which might aid understanding by reducing ambiguity inherent to the speech signal.
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Affiliation(s)
- Jared A Carter
- Institute for Intelligent Systems, University of Memphis, Memphis, TN, USA; School of Communication Sciences and Disorders, University of Memphis, Memphis, TN, USA; Division of Clinical Neuroscience, School of Medicine, Hearing Sciences - Scottish Section, University of Nottingham, Glasgow, Scotland, UK
| | - Gavin M Bidelman
- Department of Speech, Language and Hearing Sciences, Indiana University, Bloomington, IN, USA; Program in Neuroscience, Indiana University, Bloomington, IN, USA.
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