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Melo AI, Zempoalteca R, Ramirez-Funez G, Anaya-Hernández A, Porras MG, Aguirre-Benítez EL, González Del Pliego M, Armando PT, Jiménez-Estrada I. Role of tactile stimulation during the preweaning period on the development of the peripheral sensory sural (SU) nerve in adult artificially reared female rat. Dev Psychobiol 2024; 66:e22486. [PMID: 38739111 DOI: 10.1002/dev.22486] [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: 08/10/2023] [Revised: 02/19/2024] [Accepted: 03/04/2024] [Indexed: 05/14/2024]
Abstract
Maternal deprivation, as a result of the artificial rearing (AR) paradigm, disturbs electrophysiological and histological characteristics of the peripheral sensory sural (SU) nerve of infant and adult male rats. Such changes are prevented by providing tactile or social stimulation during isolation. AR also affects the female rat's brain and behavior; however, it is unknown whether this early adverse experience also alters their SU nerve development or if tactile stimulation might prevent these possible developmental effects. To assess these possibilities, the electrophysiological and histological characteristics of the SU nerve from adult diestrus AR female rats that: (i) received no tactile stimulation (AR group), (ii) received tactile stimulation in the anogenital and body area (AR-Tactile group), or (iii) were mother reared (MR group) were determined. We found that the amplitude, but not the area, of the evoked compound action potential response in SU nerves of AR rats was lower than those of SU nerves of MR female rats. Tactile stimulation prevented these effects. Additionally, we found a reduction in the outer diameter and myelin thickness of axons, as well as a large proportion of axons with low myelin thickness in nerves of AR rats compared to the nerves of the MR and AR-Tactile groups of rats; however, tactile stimulation only partially prevented these effects. Our data indicate that maternal deprivation disturbs the development of sensory SU nerves in female rats, whereas tactile stimulation partially prevents the changes generated by AR. Considering that our previous studies have shown more severe effects of AR on male SU nerve development, we suggest that sex-associated factors may be involved in these processes.
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Affiliation(s)
- Angel I Melo
- Centro de Investigación en Reproducción Animal, CINVESTAV-Laboratorio Tlaxcala, Universidad Autónoma de Tlaxcala, Ixtacuixtla, Tlaxcala, Mexico
| | - Rene Zempoalteca
- Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, Ixtacuixtla, Mexico
| | - Gabriela Ramirez-Funez
- Centro de Investigación en Reproducción Animal, CINVESTAV-Laboratorio Tlaxcala, Universidad Autónoma de Tlaxcala, Ixtacuixtla, Tlaxcala, Mexico
- Maestría en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Ixtacuixtla, Mexico
| | - Arely Anaya-Hernández
- Centro de Investigación en Genética y Ambiente, Universidad Autónoma de Tlaxcala, Ixtacuixtla, Mexico
| | - Mercedes G Porras
- Departamento de Fisiología, Facultad de Medicina, UNAM, Ciudad de México, Mexico
| | | | | | - Pérez-Torres Armando
- Departamento de Biología Celular y Tisular, Facultad de Medicina, UNAM, Ciudad de México, Mexico
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McFarlane KA, Sanchez JT. Exploring Electrode Placements to Optimize the Identification and Measurement of Early Auditory Evoked Potentials. Audiol Res 2023; 13:978-988. [PMID: 38131810 PMCID: PMC10740558 DOI: 10.3390/audiolres13060085] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/04/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023] Open
Abstract
Cochlear synaptic loss (termed cochlear synaptopathy) has been suggested to contribute to suprathreshold hearing difficulties. However, its existence and putative effects in humans remain inconclusive, largely due to the heterogeneous methods used across studies to indirectly evaluate the health of cochlear synapses. There is a need to standardize proxies of cochlear synaptopathy to appropriately compare and interpret findings across studies. Early auditory evoked potentials (AEPs), including the compound action potential (AP)/Wave I of the auditory brainstem response are a popular proxy, yet remain variable based on technical considerations. This study evaluated one such consideration-electrode array (i.e., montage)-to optimize the use of early AEP waveforms. In 35 young adults, electrocochleography (ECochG) responses were collected using vertical and horizontal montages. Standard ECochG measures and AP/Wave I and Wave II peak-to-trough amplitudes and latencies were compared between montages. Vertical montage recordings consistently produced significantly larger AP/Wave I peak-to-trough amplitudes compared to horizontal recordings. These findings support the use of a vertical electrode montage for optimal recordings of peripheral cochlear nerve activity. As cochlear synaptopathy continues to be explored in humans, the methods highlighted here should be considered in the development of a standardized assessment.
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Affiliation(s)
- Kailyn A. McFarlane
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA;
| | - Jason Tait Sanchez
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA;
- Knowles Hearing Center, Northwestern University, Evanston, IL 60208, USA
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
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Pastras CJ, Curthoys IS. Vestibular Testing-New Physiological Results for the Optimization of Clinical VEMP Stimuli. Audiol Res 2023; 13:910-928. [PMID: 37987337 PMCID: PMC10660708 DOI: 10.3390/audiolres13060079] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/05/2023] [Accepted: 11/07/2023] [Indexed: 11/22/2023] Open
Abstract
Both auditory and vestibular primary afferent neurons can be activated by sound and vibration. This review relates the differences between them to the different receptor/synaptic mechanisms of the two systems, as shown by indicators of peripheral function-cochlear and vestibular compound action potentials (cCAPs and vCAPs)-to click stimulation as recorded in animal studies. Sound- and vibration-sensitive type 1 receptors at the striola of the utricular macula are enveloped by the unique calyx afferent ending, which has three modes of synaptic transmission. Glutamate is the transmitter for both cochlear and vestibular primary afferents; however, blocking glutamate transmission has very little effect on vCAPs but greatly reduces cCAPs. We suggest that the ultrafast non-quantal synaptic mechanism called resistive coupling is the cause of the short latency vestibular afferent responses and related results-failure of transmitter blockade, masking, and temporal precision. This "ultrafast" non-quantal transmission is effectively electrical coupling that is dependent on the membrane potentials of the calyx and the type 1 receptor. The major clinical implication is that decreasing stimulus rise time increases vCAP response, corresponding to the increased VEMP response in human subjects. Short rise times are optimal in human clinical VEMP testing, whereas long rise times are mandatory for audiometric threshold testing.
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Affiliation(s)
- Christopher J. Pastras
- Faculty of Science and Engineering, School of Engineering, Macquarie University, Sydney, NSW 2109, Australia;
| | - Ian S. Curthoys
- Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW 2006, Australia
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Ciotu CI, Kistner K, Kaindl U, Millesi F, Weiss T, Radtke C, Kremer A, Schmidt K, Fischer MJM. Schwann cell stimulation induces functional and structural changes in peripheral nerves. Glia 2023; 71:945-956. [PMID: 36495059 DOI: 10.1002/glia.24316] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 11/19/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022]
Abstract
Signal propagation is the essential function of nerves. Lysophosphatidic acid 18:1 (LPA) allows the selective stimulation of calcium signaling in Schwann cells but not neurons. Here, the time course of slowing and amplitude reduction on compound action potentials due to LPA exposure was observed in myelinated and unmyelinated fibers of the mouse, indicating a clear change of axonal function. Teased nerve fiber imaging showed that Schwann cell activation is also present in axon-attached Schwann cells in freshly isolated peripheral rat nerves. The LPA receptor 1 was primarily localized at the cell extensions in isolated rat Schwann cells, suggesting a role in cell migration. Structural investigation of rat C-fibers demonstrated that LPA leads to an evagination of the axons from their Schwann cells. In A-fibers, the nodes of Ranvier appeared unchanged, but the Schmidt-Lanterman incisures were shortened and myelination reduced. The latter might increase leak current, reducing the potential spread to the next node of Ranvier and explain the changes in conduction velocity. The observed structural changes provide a plausible explanation for the functional changes in myelinated and unmyelinated axons of peripheral nerves and the reported sensory sensations such as itch and pain.
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Affiliation(s)
- Cosmin I Ciotu
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Katrin Kistner
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Ulrich Kaindl
- Department of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Flavia Millesi
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Vienna, Austria
| | - Tamara Weiss
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Vienna, Austria
| | - Christine Radtke
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Vienna, Austria
| | - Andreas Kremer
- Department of Gastroenterology and Hepatology, University Hospital Zürich, Zürich, Switzerland
| | - Katy Schmidt
- Department of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Michael J M Fischer
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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Jwair S, Ramekers D, Thomeer HGXM, Versnel H. Acute effects of cochleostomy and electrode-array insertion on compound action potentials in normal-hearing guinea pigs. Front Neurosci 2023; 17:978230. [PMID: 36845413 PMCID: PMC9945226 DOI: 10.3389/fnins.2023.978230] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 01/09/2023] [Indexed: 02/11/2023] Open
Abstract
Introduction Electrocochleography (ECochG) is increasingly used in cochlear implant (CI) surgery, in order to monitor the effect of insertion of the electrode array aiming to preserve residual hearing. However, obtained results are often difficult to interpret. Here we aim to relate changes in ECochG responses to acute trauma induced by different stages of cochlear implantation by performing ECochG at multiple time points during the procedure in normal-hearing guinea pigs. Materials and methods Eleven normal-hearing guinea pigs received a gold-ball electrode that was fixed in the round-window niche. ECochG recordings were performed during the four steps of cochlear implantation using the gold-ball electrode: (1) Bullostomy to expose the round window, (2) hand-drilling of 0.5-0.6 mm cochleostomy in the basal turn near the round window, (3) insertion of a short flexible electrode array, and (4) withdrawal of electrode array. Acoustical stimuli were tones varying in frequency (0.25-16 kHz) and sound level. The ECochG signal was primarily analyzed in terms of threshold, amplitude, and latency of the compound action potential (CAP). Midmodiolar sections of the implanted cochleas were analyzed in terms of trauma to hair cells, modiolar wall, osseous spiral lamina (OSL) and lateral wall. Results Animals were assigned to cochlear trauma categories: minimal (n = 3), moderate (n = 5), or severe (n = 3). After cochleostomy and array insertion, CAP threshold shifts increased with trauma severity. At each stage a threshold shift at high frequencies (4-16 kHz) was accompanied with a threshold shift at low frequencies (0.25-2 kHz) that was 10-20 dB smaller. Withdrawal of the array led to a further worsening of responses, which probably indicates that insertion and removal trauma affected the responses rather than the mere presence of the array. In two instances, CAP threshold shifts were considerably larger than threshold shifts of cochlear microphonics, which could be explained by neural damage due to OSL fracture. A change in amplitudes at high sound levels was strongly correlated with threshold shifts, which is relevant for clinical ECochG performed at one sound level. Conclusion Basal trauma caused by cochleostomy and/or array insertion should be minimized in order to preserve the low-frequency residual hearing of CI recipients.
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Affiliation(s)
- Saad Jwair
- Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands,UMC Utrecht Brain Center, Utrecht University, Utrecht, Netherlands
| | - Dyan Ramekers
- Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands,UMC Utrecht Brain Center, Utrecht University, Utrecht, Netherlands
| | - Hans G. X. M. Thomeer
- Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands,UMC Utrecht Brain Center, Utrecht University, Utrecht, Netherlands
| | - Huib Versnel
- Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands,UMC Utrecht Brain Center, Utrecht University, Utrecht, Netherlands,*Correspondence: Huib Versnel,
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Medler S. Effects of local anesthetics on compound action potentials generated from the frog sciatic nerve. Adv Physiol Educ 2022; 46:658-666. [PMID: 36201308 DOI: 10.1152/advan.00095.2022] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 10/04/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
The frog sciatic nerve provides a robust physiological preparation students may conveniently use to investigate the properties of compound action potentials. Electrical stimulation with standard physiology teaching equipment elicits compound action potentials that are easily recorded by upper-level undergraduate students. The amplitude of compound action potentials increases with greater stimulation voltages, up until a maximum response is achieved. Plotting action potential size as a function of stimulating voltage produces a curve that illustrates the responsiveness of a nerve. In the present study, several local anesthetics (MS-222, procaine, lidocaine, benzocaine, and tetracaine) were used to reversibly suppress compound action potentials within a time frame consistent with the limitations of teaching labs. Highly responsive nerves generate steep response curves that reach asymptotes at relatively low stimulating voltages. Less active nerves require higher stimulating voltages and appear "right-shifted." Anesthetized response curves may also appear "flatter," exhibiting lower peak amplitude, when compared to fully active nerves. The magnitude of action potential suppression and time course of recovery depended upon the specific anesthetic applied. Nerves anesthetized with MS-222 were the fastest to recover, reaching their original responsiveness within 20 min. Tetracaine had the most dramatic effects, with nerves typically requiring more than a day to fully recover physiological responses. Carefully dissected nerves maintained their physiological responses for many days when stored in Ringer solution at 4°C, making this preparation particularly useful for undergraduate lab experiences. Quantitative analyses may be performed on the data collected, providing students with opportunities to design and implement their own experiments.NEW & NOTEWORTHY The frog sciatic nerve preparation represents a "classical" physiology lab for demonstrating principles of action potentials. Local anesthetics provide an inexpensive tool to manipulate the physiological activity of nerves and other excitable tissues. Isolated nerves retain their physiological activity for up to several days when kept in Ringer solution at 4°C. Quantitative data analysis from this robust nerve preparation should present students with many opportunities for designing their own experiments with anesthetics.
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Affiliation(s)
- Scott Medler
- Physician Assistant Studies Program, School of Health Professions, St. Bonaventure University, St. Bonaventure, New York
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Martínez-Álvarez V, Segura-Alegría B, Rodríguez-Torres EE, Porras MG, Aguirre-Benítez E, González Del Pliego M, Hudson R, Quiroz-González S, Melo AI, Jiménez-Estrada I. Mother and sibling interactions during the preweaning period influence myelination and impulse propagation of the sensory sural nerve in the adult rat. Dev Psychobiol 2022; 64:e22316. [PMID: 36282737 DOI: 10.1002/dev.22316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/18/2022] [Accepted: 07/23/2022] [Indexed: 01/27/2023]
Abstract
To investigate whether mother and sibling interactions during the preweaning period influence the histological and electrophysiological characteristics of the sensory sural nerve (SUn) in the adult rat, litters composed of 1, 3, 6, 9, and 12 male pups (P) were formed and the pups routinely weighed until postnatal day 60 (PND60). At PND9, 3P and 6P litters showed greater body weight than pups without siblings or from 9P or 12P litters, and such differences in weight were maintained until adulthood. Analysis of maternal licking at PND8 and 9 showed that pups from large litters received fewer licks than pups from small size litters. At PND60, SUn of rats from 6P and 9P litters had greater compound action potential (CAP) amplitude and a higher proportion of axons with large myelin thickness than nerves from rats of 1P, 3P, or 12P litters. SUn of heaviest rats from 9P and 12P litters had greater CAP area and myelination than the lightest rats from the same litters. We propose that a complex interplay of sensory, social, and nutritional factors arising from mother and littermate interactions during the preweaning period influence myelination and the propagation of action potentials in the SUn of adult rats.
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Affiliation(s)
- Vladimir Martínez-Álvarez
- Depto. Fisiología, Biofísica y Neurociencias, CINVESTAV, IPN, Mexico City, Mexico.,Depto. Biología, FES-Iztacala, UNAM, Mexico City, Mexico
| | | | | | | | | | | | - Robyn Hudson
- Instituto de Investigaciones Biomédicas, UNAM, Mexico City, Mexico
| | | | - Angel I Melo
- Centro de Investigación en Reproducción Animal, CINVESTAV- Laboratorio Tlaxcala, Universidad Autónoma de Tlaxcala, Tlaxcala, Mexico City, Mexico
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Jennings SG, Dominguez J. Firing Rate Adaptation of the Human Auditory Nerve Optimizes Neural Signal-to-Noise Ratios. J Assoc Res Otolaryngol 2022; 23:365-378. [PMID: 35254540 PMCID: PMC9085988 DOI: 10.1007/s10162-022-00841-7] [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: 10/28/2021] [Accepted: 02/14/2022] [Indexed: 10/18/2022] Open
Abstract
Several physiological mechanisms act on the response of the auditory nerve (AN) during acoustic stimulation, resulting in an adjustment in auditory gain. These mechanisms include-but are not limited to-firing rate adaptation, dynamic range adaptation, the middle ear muscle reflex, and the medial olivocochlear reflex. A potential role of these mechanisms is to improve the neural signal-to-noise ratio (SNR) at the output of the AN in real time. This study tested the hypothesis that neural SNRs, inferred from non-invasive assessment of the human AN, improve over the duration of acoustic stimulation. Cochlear potentials were measured in response to a series of six high-level clicks embedded in a series of six lower-level broadband noise bursts. This paradigm elicited a compound action potential (CAP) in response to each click and to the onset of each noise burst. The ratio of CAP amplitudes elicited by each click and noise burst pair (i.e., neural SNR) was tracked over the six click/noise bursts. The main finding was a rapid (< 24 ms) increase in neural SNR from the first to the second click/noise burst, consistent with a real-time adjustment in the response of the auditory periphery toward improving the SNR of the signal transmitted to the brainstem. Analysis of cochlear microphonic and ear canal sound pressure recordings, as well as the time course for this improvement in neural SNR, supports the conclusion that firing rate adaptation is likely the primary mechanism responsible for improving neural SNR, while dynamic range adaptation, the middle ear muscle reflex, and the medial olivocochlear reflex played a secondary role on the effects observed in this study. Real-time improvements in neural SNR are significant because they may be essential for robust encoding of speech and other relevant stimuli in the presence of background noise.
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Affiliation(s)
- Skyler G Jennings
- Department of Communication Sciences and Disorders, The University of Utah, 390 South, 1530 East, BEHS 1201, Salt Lake City, UT, 84112, USA.
| | - Juan Dominguez
- Department of Communication Sciences and Disorders, The University of Utah, 390 South, 1530 East, BEHS 1201, Salt Lake City, UT, 84112, USA
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Andreis FR, Metcalfe B, Janjua TAM, Jensen W, Meijs S, dos Santos Nielsen TGN. The Use of the Velocity Selective Recording Technique to Reveal the Excitation Properties of the Ulnar Nerve in Pigs. Sensors (Basel) 2021; 22:58. [PMID: 35009601 PMCID: PMC8747393 DOI: 10.3390/s22010058] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/02/2021] [Accepted: 12/16/2021] [Indexed: 06/14/2023]
Abstract
Decoding information from the peripheral nervous system via implantable neural interfaces remains a significant challenge, considerably limiting the advancement of neuromodulation and neuroprosthetic devices. The velocity selective recording (VSR) technique has been proposed to improve the classification of neural traffic by combining temporal and spatial information through a multi-electrode cuff (MEC). Therefore, this study investigates the feasibility of using the VSR technique to characterise fibre type based on the electrically evoked compound action potentials (eCAP) propagating along the ulnar nerve of pigs in vivo. A range of electrical stimulation parameters (amplitudes of 50 μA-10 mA and pulse durations of 100 μs, 500 μs, 1000 μs, and 5000 μs) was applied on a cutaneous and a motor branch of the ulnar nerve in nine Danish landrace pigs. Recordings were made with a 14 ring MEC and a delay-and-add algorithm was used to convert the eCAPs into the velocity domain. The results revealed two fibre populations propagating along the cutaneous branch of the ulnar nerve, with mean velocities of 55 m/s and 21 m/s, while only one dominant fibre population was found for the motor branch, with a mean velocity of 63 m/s. Because of its simplicity to provide information on the fibre selectivity and direction of propagation of nerve fibres, VSR can be implemented to advance the performance of the bidirectional control of neural prostheses and bioelectronic medicine applications.
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Affiliation(s)
- Felipe Rettore Andreis
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, 9220 Aalborg, Denmark; (T.A.M.J.); (W.J.); (S.M.); (T.G.N.d.S.N.)
| | - Benjamin Metcalfe
- Center for Biosensors, Bioelectronics and Biodevices (C3Bio), Department of Electronic & Electrical Engineering, University of Bath, Bath BA2 7AY, UK;
| | - Taha Al Muhammadee Janjua
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, 9220 Aalborg, Denmark; (T.A.M.J.); (W.J.); (S.M.); (T.G.N.d.S.N.)
| | - Winnie Jensen
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, 9220 Aalborg, Denmark; (T.A.M.J.); (W.J.); (S.M.); (T.G.N.d.S.N.)
| | - Suzan Meijs
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, 9220 Aalborg, Denmark; (T.A.M.J.); (W.J.); (S.M.); (T.G.N.d.S.N.)
| | - Thomas Gomes Nørgaard dos Santos Nielsen
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, 9220 Aalborg, Denmark; (T.A.M.J.); (W.J.); (S.M.); (T.G.N.d.S.N.)
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Zhao D, Behzadian N, Yeomans D, Anderson TA. In Vivo Whole-Nerve Electrophysiology Setup, Action Potential Recording, and Data Analyses in a Rodent Model. Curr Protoc 2021; 1:e285. [PMID: 34748292 DOI: 10.1002/cpz1.285] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In vivo rodent, whole peripheral nerve models are useful for studying the electrical conduction of sensory and motor fibers under normal physiological conditions as well as for assessing neurological outcomes after the application of physical alterations or pharmacological agents to the nervous system. Significant literature has focused on single-neuron and central nervous system electrophysiology protocol development. However, creation and development of in vivo whole-nerve electrophysiological recording protocols are sparse in the scientific literature. Here, detailed protocols for designing and building an in vivo whole-nerve electrophysiology system are described, including straightforward techniques to create working stimulation and recording electrodes that may be adapted to numerous study designs. Further, we include details for rodent anesthesia, surgical dissection (for the sciatic nerve), compound action potential signal optimization, data acquisition, data analyses, and troubleshooting tips. © 2021 Wiley Periodicals LLC. Basic Protocol 1: In vivo electrophysiology system wiring, hardware, and software setups Support Protocol 1: Design and 3D printing of electrophysiology base electrodes Support Protocol 2: Building needle electrodes Basic Protocol 2: Rodent anesthesia and surgery for nerve exposure Basic Protocol 3: Compound action potential recording and troubleshooting using WinWCP Basic Protocol 4: Compound action potential data analysis using WinWCP.
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Affiliation(s)
- Diane Zhao
- Stanford University School of Medicine, Palo Alto, California
| | - Negin Behzadian
- Stanford University School of Medicine, Palo Alto, California
| | - David Yeomans
- Stanford University School of Medicine, Palo Alto, California
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Lajoso W, Flower G, Giacco V, Kaul A, La Mache C, Brăban A, Roxas A, Hamilton NB. Transient Receptor Potential Ankyrin-1 (TRPA1) Block Protects against Loss of White Matter Function during Ischaemia in the Mouse Optic Nerve. Pharmaceuticals (Basel) 2021; 14:ph14090909. [PMID: 34577609 PMCID: PMC8469017 DOI: 10.3390/ph14090909] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/02/2021] [Accepted: 09/03/2021] [Indexed: 11/28/2022] Open
Abstract
Oligodendrocytes produce myelin, which provides insulation to axons and speeds up neuronal transmission. In ischaemic conditions, myelin is damaged, resulting in mental and physical disabilities. Recent evidence suggests that oligodendrocyte damage during ischaemia can be mediated by Transient Receptor Potential Ankyrin-1 (TRPA1), whose activation raises intracellular Ca2+ concentrations and damages compact myelin. Here, we show that TRPA1 is constitutively active in oligodendrocytes and the optic nerve, as the specific TRPA1 antagonist, A-967079, decreases basal oligodendrocyte Ca2+ concentrations and increases the size of the compound action potential (CAP). Conversely, TRPA1 agonists reduce the size of the optic nerve CAP in an A-967079-sensitive manner. These results indicate that glial TRPA1 regulates neuronal excitability in the white matter under physiological as well as pathological conditions. Importantly, we find that inhibition of TRPA1 prevents loss of CAPs during oxygen and glucose deprivation (OGD) and improves the recovery. TRPA1 block was effective when applied before, during, or after OGD, indicating that the TRPA1-mediated damage is occurring during both ischaemia and recovery, but importantly, that therapeutic intervention is possible after the ischaemic insult. These results indicate that TRPA1 has an important role in the brain, and that its block may be effective in treating many white matter diseases.
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Ding D, Jiang H, Manohar S, Liu X, Li L, Chen GD, Salvi R. Spatiotemporal Developmental Upregulation of Prestin Correlates With the Severity and Location of Cyclodextrin-Induced Outer Hair Cell Loss and Hearing Loss. Front Cell Dev Biol 2021; 9:643709. [PMID: 34109172 PMCID: PMC8181405 DOI: 10.3389/fcell.2021.643709] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/08/2021] [Indexed: 11/24/2022] Open
Abstract
2-Hyroxypropyl-beta-cyclodextrin (HPβCD) is being used to treat Niemann-Pick C1, a fatal neurodegenerative disease caused by abnormal cholesterol metabolism. HPβCD slows disease progression, but unfortunately causes severe, rapid onset hearing loss by destroying the outer hair cells (OHC). HPβCD-induced damage is believed to be related to the expression of prestin in OHCs. Because prestin is postnatally upregulated from the cochlear base toward the apex, we hypothesized that HPβCD ototoxicity would spread from the high-frequency base toward the low-frequency apex of the cochlea. Consistent with this hypothesis, cochlear hearing impairments and OHC loss rapidly spread from the high-frequency base toward the low-frequency apex of the cochlea when HPβCD administration shifted from postnatal day 3 (P3) to P28. HPβCD-induced histopathologies were initially confined to the OHCs, but between 4- and 6-weeks post-treatment, there was an unexpected, rapid and massive expansion of the lesion to include most inner hair cells (IHC), pillar cells (PC), peripheral auditory nerve fibers, and spiral ganglion neurons at location where OHCs were missing. The magnitude and spatial extent of HPβCD-induced OHC death was tightly correlated with the postnatal day when HPβCD was administered which coincided with the spatiotemporal upregulation of prestin in OHCs. A second, massive wave of degeneration involving IHCs, PC, auditory nerve fibers and spiral ganglion neurons abruptly emerged 4–6 weeks post-HPβCD treatment. This secondary wave of degeneration combined with the initial OHC loss results in a profound, irreversible hearing loss.
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Affiliation(s)
- Dalian Ding
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Haiyan Jiang
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Senthilvelan Manohar
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Xiaopeng Liu
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Li Li
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Guang-Di Chen
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Richard Salvi
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
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13
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Silva-Alves KS, Ferreira-da-Silva FW, Coelho-de-Souza AN, Leal-Cardoso JH. Essential Oil of Croton zehntneri Prevents Conduction Alterations Produced by Diabetes Mellitus on Vagus Nerve. Plants (Basel) 2021; 10:plants10050893. [PMID: 33925228 PMCID: PMC8146017 DOI: 10.3390/plants10050893] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 12/30/2022]
Abstract
Autonomic diabetic neuropathy (ADN) is a complication of diabetes mellitus (DM), to which there is no specific treatment. In this study, the efficacy of the essential oil of Croton zehntneri (EOCz) in preventing ADN was evaluated in the rat vagus nerve. For the two fastest conducting myelinated types of axons of the vagus nerve, the conduction velocities and rheobase decreased, whilst the duration of the components of the compound action potential of these fibers increased. EOCz completely prevented these DM-induced alterations of the vagus nerve. Unmyelinated fibers were not affected. In conclusion, this investigation demonstrated that EOCz is a potential therapeutic agent for the treatment of ADN.
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Affiliation(s)
- Kerly Shamyra Silva-Alves
- Laboratory of Electrophysiology, Superior Institute of Biomedical Science, State University of Ceará, Fortaleza CEP 60.740-000, Brazil; (K.S.S.-A.); (F.W.F.-d.-S.); (A.N.C.-d.-S.)
| | - Francisco Walber Ferreira-da-Silva
- Laboratory of Electrophysiology, Superior Institute of Biomedical Science, State University of Ceará, Fortaleza CEP 60.740-000, Brazil; (K.S.S.-A.); (F.W.F.-d.-S.); (A.N.C.-d.-S.)
- Center of Exact Sciences and Technology, State University of Vale do Acaraú, Sobral CEP 62.042-030, Brazil
| | - Andrelina Noronha Coelho-de-Souza
- Laboratory of Electrophysiology, Superior Institute of Biomedical Science, State University of Ceará, Fortaleza CEP 60.740-000, Brazil; (K.S.S.-A.); (F.W.F.-d.-S.); (A.N.C.-d.-S.)
- Laboratory of Experimental Physiology, Superior Institute of Biomedical Science, State University of Ceará, Fortaleza CEP 60.740-000, Brazil
| | - José Henrique Leal-Cardoso
- Laboratory of Electrophysiology, Superior Institute of Biomedical Science, State University of Ceará, Fortaleza CEP 60.740-000, Brazil; (K.S.S.-A.); (F.W.F.-d.-S.); (A.N.C.-d.-S.)
- Correspondence: ; Tel.: +55-85-3101-9814
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14
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Abstract
PURPOSE Non-invasive estimation of the conduction velocity distribution (CVD) of a peripheral nerve has the potential to both improve clinical diagnoses of pathology and to observe the progress of the disease or the efficacy of treatments. Comparisons were made of the performance of three non-invasive CVD estimation methods proposed by independent research groups on peripheral nerve bundles under different conditions. METHODS The first method (Cummins) uses a nerve compound action potential (CAP) with temporal dispersion and a mathematical single fiber action potential (SFAP). The second method (Barker) uses two CAPs and a non-mathematical SFAP waveform. The third method (Hirose) uses two CAPs recorded from distal and proximal sites. The Cummins and Barker methods have iterative solutions in the time domain while the Hirose method is a deconvolution estimator in the frequency domain. In order to compare these methods, we used cold exposure to affect primarily motor fibers and ischemia to affect primarily sensory fibers on rat caudal nerve bundles. RESULTS The Cummins method is sensitive to changes in motor and sensory fiber percentages in CVD if it is used with the volume conductor model. The Barker and Hirose methods are sensitive to motor fiber percentages in CVD but they cannot detect changes in sensory fiber percentages accurately. CONCLUSIONS Estimation of the CVD using a priori SFAP created with a volume conductor model can non-invasively supply accurate and precise information about fiber groups in a peripheral nerve bundle.
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Affiliation(s)
- Kamil Savaş
- Medical Faculty, Department of Biophysics, Akdeniz University, Antalya, Turkey
| | - Hilmi Uysal
- Medical Faculty, Department of Neurology, Akdeniz University, Antalya, Turkey
| | - Nazmi Yaraş
- Medical Faculty, Department of Biophysics, Akdeniz University, Antalya, Turkey
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15
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Sun S, Delgado J, Behzadian N, Yeomans D, Anderson TA. Ex Vivo Whole Nerve Electrophysiology Setup, Action Potential Recording, and Data Analyses in a Rodent Model. ACTA ACUST UNITED AC 2020; 93:e99. [PMID: 32663369 DOI: 10.1002/cpns.99] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Ex vivo rodent whole nerves provide a model for assessing the effects of interventions on nerve impulse transmission and consequent sensory and/or motor function. Nerve impulse transmission can be measured through sciatic nerve compound action potential (CAP) recordings. However, de novo development and implementation of an ex vivo whole nerve resection protocol and an electrophysiology setup that retains nerve viability, that produces low noise CAP signals, and that allows for data analysis is challenging. Additionally, some of the existing literature lacks detail and accuracy and may be out of date. This article describes detailed protocols for rodent ex vivo sciatic nerve dissection and handling; importance of an optimal physiologic solution; computer-aided designs for 3D printing of readily adaptable ex vivo rodent whole nerve electrophysiology chambers; construction of low-cost, effective suction electrodes; setup and use of nerve stimulators and amplifiers; acquisition of low noise, small voltage CAP data and digital conversion; use of software for data analyses of CAP components; and tips for troubleshooting. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Electrophysiology wiring and hardware setup Support Protocol 1: 3D printing an electrophysiology chamber Support Protocol 2: Building suction electrodes Basic Protocol 2: Sciatic nerve dissection and compound action potential recording Basic Protocol 3: Data export and analysis Support Protocol 3: Preparation of HEPES-buffered physiologic solution.
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Affiliation(s)
- Sharon Sun
- University of Texas Southwestern Medical School, Dallas, Texas
| | - Jorge Delgado
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California
| | | | - David Yeomans
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California
| | - Thomas Anthony Anderson
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California
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16
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Kumamoto E. Inhibition of Fast Nerve Conduction Produced by Analgesics and Analgesic Adjuvants-Possible Involvement in Pain Alleviation. Pharmaceuticals (Basel) 2020; 13:E62. [PMID: 32260535 DOI: 10.3390/ph13040062] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 03/29/2020] [Accepted: 04/01/2020] [Indexed: 02/07/2023] Open
Abstract
Nociceptive information is transmitted from the periphery to the cerebral cortex mainly by action potential (AP) conduction in nerve fibers and chemical transmission at synapses. Although this nociceptive transmission is largely inhibited at synapses by analgesics and their adjuvants, it is possible that the antinociceptive drugs inhibit nerve AP conduction, contributing to their antinociceptive effects. Many of the drugs are reported to inhibit the nerve conduction of AP and voltage-gated Na+ and K+ channels involved in its production. Compound action potential (CAP) is a useful measure to know whether drugs act on nerve AP conduction. Clinically-used analgesics and analgesic adjuvants (opioids, non-steroidal anti-inflammatory drugs, 2-adrenoceptor agonists, antiepileptics, antidepressants and local anesthetics) were found to inhibit fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Similar actions were produced by antinociceptive plant-derived chemicals. Their inhibitory actions depended on the concentrations and chemical structures of the drugs. This review article will mention the inhibitory actions of the antinociceptive compounds on CAPs in frog and mammalian peripheral (particularly, sciatic) nerves and on voltage-gated Na+ and K+ channels involved in AP production. Nerve AP conduction inhibition produced by analgesics and analgesic adjuvants is suggested to contribute to at least a part of their antinociceptive effects.
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17
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Abstract
The transient receptor potential vanilloid member 1 (TRPV1) in the central nervous system may contribute to homeostatic plasticity by regulating intracellular Ca2+, which becomes unbalanced in age-related neurodegenerative diseases, including Alzheimer’s and Huntington’s. Glaucomatous optic neuropathy – the world’s leading cause of irreversible blindness – involves progressive degeneration of retinal ganglion cell (RGC) axons in the optic nerve through sensitivity to stress related to intraocular pressure (IOP). In models of glaucoma, genetic deletion of TRPV1 (Trpv1–/–) accelerates RGC axonopathy in the optic projection, whereas TRPV1 activation modulates RGC membrane polarization. In continuation of these studies, here, we found that Trpv1–/– increases the compound action potential (CAP) of optic nerves subjected to short-term elevations in IOP. This IOP-induced increase in CAP was not directly due to TRPV1 channels in the optic nerve, because the TRPV1-selective antagonist iodoresiniferatoxin had no effect on the CAP for wild-type optic nerve. Rather, the enhanced CAP in Trpv1–/– optic nerve was associated with increased expression of the voltage-gated sodium channel subunit 1.6 (NaV1.6) in longer nodes of Ranvier within RGC axons, rendering Trpv1–/– optic nerve relatively insensitive to NaV1.6 antagonism via 4,9-anhydrotetrodotoxin. These results indicate that with short-term elevations in IOP, Trpv1–/– increases axon excitability through greater NaV1.6 localization within longer nodes. In neurodegenerative disease, native TRPV1 may tune NaV expression in neurons under stress to match excitability to available metabolic resources.
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Affiliation(s)
- Nolan R McGrady
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Michael L Risner
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Victoria Vest
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
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18
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Lee C, Valenzuela CV, Goodman SS, Kallogjeri D, Buchman CA, Lichtenhan JT. Early Detection of Endolymphatic Hydrops using the Auditory Nerve Overlapped Waveform (ANOW). Neuroscience 2020; 425:251-266. [PMID: 31809731 PMCID: PMC6935415 DOI: 10.1016/j.neuroscience.2019.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [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: 08/19/2019] [Revised: 10/30/2019] [Accepted: 11/04/2019] [Indexed: 01/14/2023]
Abstract
Endolymphatic hydrops is associated with low-frequency sensorineural hearing loss, with a large body of research dedicated to examining its putative causal role in low-frequency hearing loss. Investigations have been thwarted by the fact that hearing loss is measured in intact ears, but gold standard assessments of endolymphatic hydrops are made postmortem only; and that no objective low-frequency hearing measure has existed. Yet the association of endolymphatic hydrops with low-frequency hearing loss is so strong that it has been established as one of the important defining features for Ménière's disease, rendering it critical to detect endolymphatic hydrops early, regardless of whether it serves a causal role or is the result of other disease mechanisms. We surgically induced endolymphatic hydrops in guinea pigs and employed our recently developed objective neural measure of low-frequency hearing, the Auditory Nerve Overlapped Waveform (ANOW). Hearing loss and endolymphatic hydrops were assessed at various time points after surgery. The ANOW detected low-frequency hearing loss as early as the first day after surgery, well before endolymphatic hydrops was found histologically. The ANOW detected low-frequency hearing loss with perfect sensitivity and specificity in all ears after endolymphatic hydrops developed, where there was a strong linear relationship between degree of endolymphatic hydrops and severity of low-frequency hearing loss. Further, histological data demonstrated that endolymphatic hydrops is seen first in the high-frequency cochlear base, though the ANOW demonstrated that dysfunction begins in the low-frequency apical cochlear half. The results lay the groundwork for future investigations of the causal role of endolymphatic hydrops in low-frequency hearing loss.
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Affiliation(s)
- C Lee
- Washington University School of Medicine in St. Louis, Department of Otolaryngology, Saint Louis, MO, USA
| | - C V Valenzuela
- Washington University School of Medicine in St. Louis, Department of Otolaryngology, Saint Louis, MO, USA
| | - S S Goodman
- University of Iowa, Department of Communication Sciences and Disorders, Iowa City, IA, USA
| | - D Kallogjeri
- Washington University School of Medicine in St. Louis, Department of Otolaryngology, Saint Louis, MO, USA
| | - C A Buchman
- Washington University School of Medicine in St. Louis, Department of Otolaryngology, Saint Louis, MO, USA
| | - J T Lichtenhan
- Washington University School of Medicine in St. Louis, Department of Otolaryngology, Saint Louis, MO, USA.
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19
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Yamate-Morgan H, Lauderdale K, Horeczko J, Merchant U, Tiwari-Woodruff SK. Functional Effects of Cuprizone-Induced Demyelination in the Presence of the mTOR-Inhibitor Rapamycin. Neuroscience 2019; 406:667-683. [PMID: 30703503 PMCID: PMC6682545 DOI: 10.1016/j.neuroscience.2019.01.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [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: 09/06/2018] [Revised: 01/19/2019] [Accepted: 01/21/2019] [Indexed: 01/09/2023]
Abstract
Persistent demyelination has been implicated in axon damage and functional deficits underlying neurodegenerative diseases such as multiple sclerosis. The cuprizone diet model of demyelination allows for the investigation of mechanisms underlying timed and reproducible demyelination and remyelination. However, spontaneous oligodendrocyte (OL) progenitor (OPC) proliferation, OPC differentiation, and axon remyelination during cuprizone diet may convolute the understanding of remyelinating events. The Akt (a serine/threonine kinase)/mTOR (the mammalian target of rapamycin) signaling pathway in OLs regulates intermediate steps during myelination. Thus, in an effort to inhibit spontaneous remyelination, the mTOR inhibitor rapamycin has been administered during cuprizone diet. Intrigued by the potential for rapamycin to optimize the cuprizone model by producing more complete demyelination, we sought to characterize the effects of rapamycin on axonal function and myelination. Functional remyelination was assessed by callosal compound action potential (CAP) recordings along with immunohistochemistry in mice treated with rapamycin during cuprizone diet. Rapamycin groups exhibited similar myelination, but significantly increased axonal damage and inflammation compared to non-rapamycin groups. There was minimal change in CAP amplitude between groups, however, a significant decrease in conduction velocity of the slower, non-myelinated CAP component was observed in the rapamycin group relative to the non-rapamycin group. During remyelination, rapamycin groups showed a significant decrease in OPC proliferation and mature OLs, suggesting a delay in OPC differentiation kinetics. In conclusion, we question the use of rapamycin to produce consistent demyelination as rapamycin increased inflammation and axonal damage, without affecting myelination.
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Affiliation(s)
- Hana Yamate-Morgan
- Department of Neuroscience, University of California, Riverside (UCR), Riverside, CA 92521, USA; Division of Biomedical Sciences, UCR School of Medicine, Riverside, CA 92521, USA
| | - Kelli Lauderdale
- Division of Biomedical Sciences, UCR School of Medicine, Riverside, CA 92521, USA
| | - Joshua Horeczko
- Division of Biomedical Sciences, UCR School of Medicine, Riverside, CA 92521, USA
| | - Urja Merchant
- Division of Biomedical Sciences, UCR School of Medicine, Riverside, CA 92521, USA
| | - Seema K Tiwari-Woodruff
- Department of Neuroscience, University of California, Riverside (UCR), Riverside, CA 92521, USA; Division of Biomedical Sciences, UCR School of Medicine, Riverside, CA 92521, USA; Center for Glial-Neuronal Interactions, UCR School of Medicine, CA 92521.
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20
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Abstract
Ultrasonic (US) neuromodulation has emerged as a promising therapeutic means by delivering focused energy deep into the tissue. Low-intensity ultrasound (US) directly activates and/or inhibits neurons in the central nervous system (CNS). US neuromodulation of the peripheral nervous system (PNS) is less developed and rarely used clinically. Literature on the neuromodulatory effects of US on the PNS is controversy with some documenting enhanced neural activities, some showing suppressed activities, and others reporting mixed effects. US, with different range of intensity and strength, is likely to generate distinct physical effects in the stimulated neuronal tissues, which underlies different experimental outcomes in the literature. In this review, we summarize all the major reports that documented the effects of US on peripheral nerve endings, axons, and/or somata in the dorsal root ganglion. In particular, we thoroughly discuss the potential impacts by the following key parameters to the study outcomes of PNS neuromodulation by the US: frequency, pulse repetition frequency, duty cycle, intensity, metrics for peripheral neural activities, and type of biological preparations used in the studies. Potential mechanisms of peripheral US neuromodulation are summarized to provide a plausible interpretation to the seemly contradictory effects of enhanced and suppressed neural activities from US neuromodulation.
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Affiliation(s)
- Bin Feng
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
- Correspondence: ; Tel.: (001-860-486-6435)
| | - Longtu Chen
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - Sheikh J. Ilham
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
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21
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Li S, Ye F, Farber JP, Linderoth B, Zhang T, Gu JW, Moffitt M, Garrett K, Chen J, Foreman RD. Dependence of c-fos Expression on Amplitude of High-Frequency Spinal Cord Stimulation in a Rodent Model. Neuromodulation 2018; 22:172-178. [PMID: 30221804 DOI: 10.1111/ner.12852] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 06/01/2018] [Accepted: 06/26/2018] [Indexed: 12/18/2022]
Abstract
OBJECTIVES Clinical high-frequency spinal cord stimulation (hfSCS) (>250 Hz) applied at subperception amplitudes reduces leg and low back pain. This study investigates, via labeling for c-fos-a marker of neural activation, whether 500 Hz hfSCS applied at amplitudes above and below the dorsal column (DC) compound action potential (CAP) threshold excites dorsal horn neurons. MATERIALS AND METHODS DC CAP thresholds in rats were determined by applying single biphasic pulses of SCS to T12 -T13 segments using pulse widths of 40 or 200 μsec via a ball electrode placed over the left DC and increasing amplitude until a short latency CAP was observed on the L5 DC and sciatic nerve. The result of this comparison allowed us to substitute sciatic nerve CAP for DC CAP. SCS at T12 -T13 was applied continuously for two hours using: sham or hfSCS at 500 Hz SCS, 40 μsec pulse width, and 50, 70, 90, or 140% CAP threshold. Spinal cord slices from T11 -L1 were immunolabeled for c-fos, and the number of c-fos-positive cells was quantified. RESULTS 500 Hz hfSCS applied at 90 and 140% CAP threshold produced substantial (≥6 c-fos + neurons on average per slice per segment) c-fos expression in more segments between T11 and L1 than did sham stimulation (p < 0.025, 90% CAP; p < 0.001, 140% CAP, Fisher's Exact Tests) and resulted in more c-fos-positive neurons on average per slice per segment ipsilateral to than contralateral to the SCS electrode at 70, 90, and 140% CAP threshold (p < 0.01, Wilcoxon Signed Rank Tests). CONCLUSIONS The finding of enhanced c-fos expression in the ipsilateral superficial dorsal horn provides evidence for activation/modulation of neuronal circuitry associated with subperception hfSCS.
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Affiliation(s)
- Shiying Li
- Veterans Research Education Foundation, VA Medical Center, Oklahoma City, OK, USA.,Division of Gastroenterology and Hepatology, Johns Hopkins University, Baltimore, MD, USA
| | - Feng Ye
- Veterans Research Education Foundation, VA Medical Center, Oklahoma City, OK, USA.,Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA.,Infectious Disease Department, the First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Jay P Farber
- Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Bengt Linderoth
- Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA.,Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | | | | | | | - Kennon Garrett
- Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Jiande Chen
- Division of Gastroenterology and Hepatology, Johns Hopkins University, Baltimore, MD, USA.,Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Robert D Foreman
- Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA.,Department of Anesthesiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
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22
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Leggett K, Mendis V, Mulders W. Divergent Responses in the Gap Prepulse Inhibition of the Acoustic Startle Reflex in Two Different Guinea Pig Colonies. Int Tinnitus J 2018; 22:1-9. [PMID: 29993210 DOI: 10.5935/0946-5448.20180001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Animal models of tinnitus rely on interpretation of behavioural or reflexive tests to determine the presence of this phantom perception. A commonly used test is the gap prepulse inhibition of acoustic startle (GPIAS), which is often combined with prepulse inhibition (PPI) to ensure that reduced GPIAS suppression is not due to hearing loss caused by the acoustic trauma commonly used to trigger tinnitus development. In our laboratory GPIAS and PPI are routinely used on two colonies of outbred tri-colour guinea pigs. However, our results show that these colonies show divergent results even before any tinnitus-inducing treatment, which impacts their suitability in tinnitus models. Although colony 1 and 2 show similar results in PPI (~95% of animals showing significant suppression), only ~30% of colony 2 also shows significant suppression in GPIAS compared to ~75% of colony 1. Cochlear sensitivity measured using compound action potentials showed no significant differences between colonies. Therefore, peripheral threshold loss was excluded as a possible factor. Our results show that similar strains of laboratory animals can show highly divergent results and GPIAS testing for tinnitus will not work for every animal strain. In addition, our data support the notion that PPI and GPIAS responses may rely on different neural circuitry.
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Affiliation(s)
- K Leggett
- School of Human Sciences, University of Western Australia, Crawley, Western Australia, Australia
| | - V Mendis
- School of Human Sciences, University of Western Australia, Crawley, Western Australia, Australia
| | - Wham Mulders
- School of Human Sciences, University of Western Australia, Crawley, Western Australia, Australia.,Ear Science Institute Australia, Subiaco, Western Australia, Australia
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23
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Henry KS, Abrams KS. Persistent Auditory Nerve Damage Following Kainic Acid Excitotoxicity in the Budgerigar (Melopsittacus undulatus). J Assoc Res Otolaryngol 2018; 19:435-449. [PMID: 29744730 DOI: 10.1007/s10162-018-0671-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 04/22/2018] [Indexed: 11/30/2022] Open
Abstract
Permanent loss of auditory nerve (AN) fibers occurs with increasing age and sound overexposure, sometimes without hair cell damage or associated audiometric threshold elevation. Rodent studies suggest effects of AN damage on central processing and behavior, but these species have limited capacity to discriminate low-frequency speech-like sounds. Here, we introduce a new animal model of AN damage in an avian communication specialist, the budgerigar (Melopsittacus undulatus). The budgerigar is a vocal learner and speech mimic with sensitive low-frequency hearing and human-like behavioral sensitivity to many complex signals including speech components. Excitotoxic AN damage was induced through bilateral cochlear infusions of kainic acid (KA). Acute KA effects on cochlear function were assessed using AN compound action potentials (CAPs) and hair cell cochlear microphonics (CMs). Long-term KA effects were assessed using auditory brainstem response (ABR) measurements for up to 31 weeks post-KA exposure. KA infusion immediately abolished AN CAPs while having mild impact on the CM. ABR wave I, the far-field AN response, showed a pronounced 40-75 % amplitude reduction at moderate-to-high sound levels that persisted for the duration of the study. In contrast, wave I latency and the amplitude of wave V were nearly unaffected by KA, and waves II-IV were less reduced than wave I. ABR thresholds, calculated based on complete response waveforms, showed no impairment following KA. These results demonstrate that KA exposure in the budgerigar causes irreversible AN damage, most likely through excitotoxic injury to afferent fibers or synapses as in other species, while sparing ABR thresholds. Normal wave V amplitude, assumed to originate centrally, may persist through compensatory mechanisms that restore central response amplitude by downregulating inhibition. Future studies in this new animal model of AN damage can explore effects of this neural lesion, in isolation from hair cell trauma and threshold elevation, on central processing and perception of complex sounds.
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Affiliation(s)
- Kenneth S Henry
- Department of Otolaryngology, University of Rochester, 601 Elmwood Ave., Box 629, Rochester, NY, 14642, USA.
| | - Kristina S Abrams
- Department of Otolaryngology, University of Rochester, 601 Elmwood Ave., Box 629, Rochester, NY, 14642, USA.,Department of Neuroscience, University of Rochester, Rochester, NY, USA
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24
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Abstract
KEY POINTS We have developed an improved method that enables simultaneous recording of stimulus evoked compound action potentials from large myelinated A fibres and small unmyelinated C fibres in mouse sciatic nerves. Investigations into the ability of fructose to support conduction in sciatic nerve revealed a novel glia-to-axon metabolic pathway in which fructose is converted in Schwann cells to lactate for subsequent shuttling to A fibres. The C fibres most likely directly take up and metabolise fructose. These differences are indicative of fibre sub-type specific metabolic profiles. These results demonstrate that the physiological insights provided by the method can be applied to investigations of peripheral nerve, with a view to understanding the metabolic disruptions that underlie diabetic neuropathy. ABSTRACT The stimulus evoked compound action potential (CAP), recorded using suction electrodes, provides an index of the relative number of conducting axons within a nerve trunk. As such the CAP has been used to elucidate the diverse mechanisms of injury resulting from a variety of metabolic insults to central nervous white matter, whilst also providing a model with which to assess the benefits of clinically relevant neuroprotective strategies. In addition the technique lends itself to the study of metabolic cell-to-cell signalling that occurs between glial cells and neurones, and to exploring the ability of non-glucose substrates to support axon conduction. Although peripheral nerves are sensitive to metabolic insult and are susceptible to diabetic neuropathy, there is a lack of fundamental information regarding peripheral nerve metabolism. A confounding factor in such studies is the extended duration demanded by the experimental protocol, requiring stable recording for periods of many hours. We describe a method that allows us to record simultaneously the stimulus evoked CAPs from A and C fibres from mouse sciatic nerve, and demonstrate its utility as applied to investigations into fibre sub-type substrate use. Our results suggest that C fibres directly take up and metabolise fructose, whereas A fibre conduction is supported by fructose-derived lactate, implying there exist unique metabolic profiles in neighbouring fibre sub-types present within the same nerve trunk.
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Affiliation(s)
- Laura R Rich
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Angus M Brown
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK.,Department of Neurology, School of Medicine, University of Washington, Seattle, WA, 98195, USA
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Zempoalteca R, Porras MG, Moreno-Pérez S, Ramirez-Funez G, Aguirre-Benítez EL, González Del Pliego M, Mariscal-Tovar S, Mendoza-Garrido ME, Hoffman KL, Jiménez-Estrada I, Melo AI. Early postnatal development of electrophysiological and histological properties of sensory sural nerves in male rats that were maternally deprived and artificially reared: Role of tactile stimulation. Dev Neurobiol 2017; 78:351-362. [PMID: 29197166 DOI: 10.1002/dneu.22561] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 11/14/2017] [Accepted: 11/25/2017] [Indexed: 12/12/2022]
Abstract
Early adverse experiences disrupt brain development and behavior, but little is known about how such experiences impact on the development of the peripheral nervous system. Recently, we found alterations in the electrophysiological and histological characteristics of the sensory sural (SU) nerve in maternally deprived, artificially reared (AR) adult male rats, as compared with maternally reared (MR) control rats. In the present study, our aim was to characterize the ontogeny of these alterations. Thus, male pups of four postnatal days (PND) were (1) AR group, (2) AR and received daily tactile stimulation to the body and anogenital region (AR-Tactile group); or (3) reared by their mother (MR group). At PND 7, 14, or 21, electrophysiological properties and histological characteristics of the SU nerves were assessed. At PND 7, the electrophysiological properties and most histological parameters of the SU nerve did not differ among MR, AR, and AR-Tactile groups. By contrast, at PND 14 and/or 21, the SU nerve of AR rats showed a lower CAP amplitude and area, and a significant reduction in myelin area and myelin thickness, which were accompanied by a reduction in axon area (day 21 only) compared to the nerves of MR rats. Tactile stimulation (AR-Tactile group) partially prevented most of these alterations. These results suggest that sensory cues from the mother and/or littermates during the first 7-14 PND are relevant for the proper development and function of the adult SU nerve. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 351-362, 2018.
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Affiliation(s)
- Rene Zempoalteca
- Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, México
| | | | - Suelem Moreno-Pérez
- Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, México.,Maestría en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, México
| | - Gabriela Ramirez-Funez
- Maestría en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, México.,Centro de Investigación en Reproducción Animal, CINVESTAV-Laboratorio Tlaxcala, Universidad Autónoma de Tlaxcala, México
| | | | | | | | | | - Kurt Leroy Hoffman
- Centro de Investigación en Reproducción Animal, CINVESTAV-Laboratorio Tlaxcala, Universidad Autónoma de Tlaxcala, México
| | | | - Angel I Melo
- Centro de Investigación en Reproducción Animal, CINVESTAV-Laboratorio Tlaxcala, Universidad Autónoma de Tlaxcala, México
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Harris KC, Vaden KI, McClaskey CM, Dias JW, Dubno JR. Complementary metrics of human auditory nerve function derived from compound action potentials. J Neurophysiol 2017; 119:1019-1028. [PMID: 29187555 DOI: 10.1152/jn.00638.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Declines in auditory nerve (AN) function contribute to suprathreshold auditory processing and communication deficits in individuals with normal hearing, hearing loss, hyperacusis, and tinnitus. Procedures to characterize AN loss or dysfunction in humans are limited. We report several novel complementary metrics using the compound action potential (CAP), a direct measure of summated AN activity. Together, these metrics may be used to characterize AN function noninvasively in humans. We examined how these metrics change with stimulus intensity and interpreted these changes within a framework of known physiological properties of the basilar membrane and AN. Our results reveal how neural synchrony and the recruitment of AN fibers with longer first-spike latencies likely contribute to the CAP, affect auditory processing, and differ with noise exposure history in younger adults with normal pure-tone thresholds. Moving forward, this new battery of metrics provides a crucial step toward new diagnostics of AN function in humans. NEW & NOTEWORTHY Loss or inactivity of auditory nerve (AN) fibers is thought to contribute to suprathreshold auditory processing deficits, but evidence-based methods to assess these effects are not available. We describe several novel metrics that together may be used to quantify neural synchrony and characterize AN function in humans.
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Affiliation(s)
- Kelly C Harris
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina , Charleston, South Carolina
| | - Kenneth I Vaden
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina , Charleston, South Carolina
| | - Carolyn M McClaskey
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina , Charleston, South Carolina
| | - James W Dias
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina , Charleston, South Carolina
| | - Judy R Dubno
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina , Charleston, South Carolina
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Ding D, Jiang H, Chen GD, Longo-Guess C, Muthaiah VPK, Tian C, Sheppard A, Salvi R, Johnson KR. N-acetyl-cysteine prevents age-related hearing loss and the progressive loss of inner hair cells in γ-glutamyl transferase 1 deficient mice. Aging (Albany NY) 2017; 8:730-50. [PMID: 26977590 PMCID: PMC4925825 DOI: 10.18632/aging.100927] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Accepted: 02/18/2016] [Indexed: 02/07/2023]
Abstract
Genetic factors combined with oxidative stress are major determinants of age-related hearing loss (ARHL), one of the most prevalent disorders of the elderly. Dwarf grey mice, Ggt1dwg/dwg, are homozygous for a loss of function mutation of the γ-glutamyl transferase 1 gene, which encodes an important antioxidant enzyme critical for the resynthesis of glutathione (GSH). Since GSH reduces oxidative damage, we hypothesized that Ggt1dwg/dwg mice would be susceptible to ARHL. Surprisingly, otoacoustic emissions and cochlear microphonic potentials, which reflect cochlear outer hair cell (OHC) function, were largely unaffected in mutant mice, whereas auditory brainstem responses and the compound action potential were grossly abnormal. These functional deficits were associated with an unusual and selective loss of inner hair cells (IHC), but retention of OHC and auditory nerve fibers. Remarkably, hearing deficits and IHC loss were completely prevented by N-acetyl-L-cysteine, which induces de novo synthesis of GSH; however, hearing deficits and IHC loss reappeared when treatment was discontinued. Ggt1dwg/dwgmice represent an important new model for investigating ARHL, therapeutic interventions, and understanding the perceptual and electrophysiological consequences of sensory deprivation caused by the loss of sensory input exclusively from IHC.
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Affiliation(s)
- Dalian Ding
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA
| | - Haiyan Jiang
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA
| | - Guang-Di Chen
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA
| | | | | | - Cong Tian
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Adam Sheppard
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA
| | - Richard Salvi
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA
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Smith SB, Lichtenhan JT, Cone BK. Contralateral Inhibition of Click- and Chirp-Evoked Human Compound Action Potentials. Front Neurosci 2017; 11:189. [PMID: 28420960 PMCID: PMC5378791 DOI: 10.3389/fnins.2017.00189] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 03/21/2017] [Indexed: 11/13/2022] Open
Abstract
Cochlear outer hair cells (OHC) receive direct efferent feedback from the caudal auditory brainstem via the medial olivocochlear (MOC) bundle. This circuit provides the neural substrate for the MOC reflex, which inhibits cochlear amplifier gain and is believed to play a role in listening in noise and protection from acoustic overexposure. The human MOC reflex has been studied extensively using otoacoustic emissions (OAE) paradigms; however, these measurements are insensitive to subsequent "downstream" efferent effects on the neural ensembles that mediate hearing. In this experiment, click- and chirp-evoked auditory nerve compound action potential (CAP) amplitudes were measured electrocochleographically from the human eardrum without and with MOC reflex activation elicited by contralateral broadband noise. We hypothesized that the chirp would be a more optimal stimulus for measuring neural MOC effects because it synchronizes excitation along the entire length of the basilar membrane and thus evokes a more robust CAP than a click at low to moderate stimulus levels. Chirps produced larger CAPs than clicks at all stimulus intensities (50-80 dB ppeSPL). MOC reflex inhibition of CAPs was larger for chirps than clicks at low stimulus levels when quantified both in terms of amplitude reduction and effective attenuation. Effective attenuation was larger for chirp- and click-evoked CAPs than for click-evoked OAEs measured from the same subjects. Our results suggest that the chirp is an optimal stimulus for evoking CAPs at low stimulus intensities and for assessing MOC reflex effects on the auditory nerve. Further, our work supports previous findings that MOC reflex effects at the level of the auditory nerve are underestimated by measures of OAE inhibition.
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Affiliation(s)
- Spencer B Smith
- Department of Speech, Language, and Hearing Sciences, University of ArizonaTucson, AZ, USA
| | - Jeffery T Lichtenhan
- Department of Otolaryngology, Washington University School of MedicineSt. Louis, MO, USA
| | - Barbara K Cone
- Department of Speech, Language, and Hearing Sciences, University of ArizonaTucson, AZ, USA
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Abstract
Before 1964, electrocochleography (ECochG) was a surgical procedure carried out in the operating theatre. Currently, the newest application is also an intra-operative one, often carried out in conjunction with cochlear implant surgery. Starting in 1967, the recording methods became either minimal- or not-invasive, i.e., trans-tympanic (TT) or extra tympanic (ET), and included extensive studies of the arguments pro and con. I will review several valuable applications of ECochG, from a historical point of view, but covering all 75 years if applicable. The main topics will be: (1) comparing human and animal cochlear electrophysiology; (2) the use in objective audiometry involving tone pip stimulation-currently mostly pre cochlear implantation but otherwise replaced by auditory brainstem response (ABR) recordings; (3) attempts to diagnose Ménière's disease and the role of the summating potential (SP); (4) early use in diagnosing vestibular schwannomas-now taken over by ABR screening and MRI confirmation; (5) relating human electrophysiology to the effects of genes as in auditory neuropathy; and (6) intracochlear recording using the cochlear implant electrodes. The last two applications are the most recently added ones. The "historical aspects" of this review article will highlight the founding years prior to 1980 when relevant. A survey of articles on Pubmed shows several ups and downs in the clinical interest as reflected in the publication counts over the last 75 years.
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Affiliation(s)
- Jos J. Eggermont
- Department of Psychology, University of CalgaryCalgary, AB, Canada
- Department of Physiology and Pharmacology, University of CalgaryCalgary, AB, Canada
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30
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Abouelela A, Wieraszko A. The Influence of Glutamate on Axonal Compound Action Potential In Vitro. J Brachial Plex Peripher Nerve Inj 2017; 11:e29-e37. [PMID: 28077958 DOI: 10.1055/s-0036-1593441] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 08/14/2016] [Indexed: 10/20/2022] Open
Abstract
Background Our previous experiments demonstrated modulation of the amplitude of the axonal compound action potential (CAP) by electrical stimulation. To verify assumption that glutamate released from axons could be involved in this phenomenon, the modification of the axonal CAP induced by glutamate was investigated. Objectives The major objective of this research is to verify the hypothesis that axonal activity would trigger the release of glutamate, which in turn would interact with specific axonal receptors modifying the amplitude of the action potential. Methods Segments of the sciatic nerve were exposed to exogenous glutamate in vitro, and CAP was recorded before and after glutamate application. In some experiments, the release of radioactive glutamate analog from the sciatic nerve exposed to exogenous glutamate was also evaluated. Results The glutamate-induced increase in CAP was blocked by different glutamate receptor antagonists. The effect of glutamate was not observed in Ca-free medium, and was blocked by antagonists of calcium channels. Exogenous glutamate, applied to the segments of sciatic nerve, induced the release of radioactive glutamate analog, demonstrating glutamate-induced glutamate release. Immunohistochemical examination revealed that axolemma contains components necessary for glutamatergic neurotransmission. Conclusion The proteins of the axonal membrane can under the influence of electrical stimulation or exogenous glutamate change membrane permeability and ionic conductance, leading to a change in the amplitude of CAP. We suggest that increased axonal activity leads to the release of glutamate that results in changes in the amplitude of CAPs.
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Affiliation(s)
- Ahmed Abouelela
- Department of Biology, The College of Staten Island, City University of New York, New York, NY, USA; Program in Neuroscience, The College of Staten Island, City University of New York, New York, NY, USA
| | - Andrzej Wieraszko
- Department of Biology, The College of Staten Island, City University of New York, New York, NY, USA; Program in Neuroscience, The College of Staten Island, City University of New York, New York, NY, USA; Graduate Center, City University of New York, New York, USA
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31
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Wu CC, Luo X. Excitation Patterns of Standard and Steered Partial Tripolar Stimuli in Cochlear Implants. J Assoc Res Otolaryngol 2015; 17:145-58. [PMID: 26691160 DOI: 10.1007/s10162-015-0549-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [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: 01/01/2015] [Accepted: 11/25/2015] [Indexed: 11/25/2022] Open
Abstract
Current steering in partial tripolar (pTP) mode has been shown to improve pitch perception and spectral resolution with cochlear implants (CIs). In this mode, a fraction (σ) of the main electrode current is returned within the cochlea and steered between the basal and apical flanking electrodes (with a proportion of α and 1 - α, respectively). Pitch generally decreases when α increases from 0 to 1, although the salience of pitch change varies across CI users. This study aimed to identify the mechanism of pitch changes with pTP-mode current steering and the factors contributing to the intersubject variability in pitch-ranking sensitivity. The electrical fields were measured for steered pTP stimuli on the same main electrode with α = 0, 0.5, and 1 in five implanted ears using electrical field imaging (EFI). The related excitation patterns were also measured physiologically using evoked compound action potential (ECAP) and psychophysically using psychophysical forward masking (PFM). Consistent with the pitch-ranking results in this study, the EFI, ECAP, and PFM centroids shifted apically with increasing α. An apical shift was also observed for the PFM peak but not for the EFI or ECAP peak. The pattern width was similar with different α values within a given measure (e.g., EFI, ECAP, or PFM), but the ECAP patterns were broader than the EFI and PFM patterns, possibly because ECAP was measured with smaller σ values than EFI and PFM. The amount of pattern shift with α depended on σ (i.e., the total amount of current used for steering) but was not correlated with the pitch-ranking sensitivity across subjects. The results revealed that the pitch changes elicited by pTP-mode current steering were not only driven by the shifts of excitation centroid.
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Affiliation(s)
- Ching-Chih Wu
- Department of Speech, Language, and Hearing Sciences, Purdue University, 715 Clinic Drive, West Lafayette, IN, 47907, USA
- School of Electrical and Computer Engineering, Purdue University, 715 Clinic Drive, West Lafayette, IN, 47907, USA
| | - Xin Luo
- Department of Speech, Language, and Hearing Sciences, Purdue University, 715 Clinic Drive, West Lafayette, IN, 47907, USA.
- Department of Speech and Hearing Science, Arizona State University, Coor Hall, 975 S. Myrtle Av., P. O. Box 870102, Tempe, AZ, 85287, USA.
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Charaziak KK, Siegel JH. Tuning of SFOAEs Evoked by Low-Frequency Tones Is Not Compatible with Localized Emission Generation. J Assoc Res Otolaryngol 2015; 16:317-29. [PMID: 25813430 PMCID: PMC4417092 DOI: 10.1007/s10162-015-0513-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [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: 06/05/2014] [Accepted: 02/17/2015] [Indexed: 12/20/2022] Open
Abstract
Stimulus-frequency otoacoustic emissions (SFOAEs) appear to be well suited for assessing frequency selectivity because, at least on theoretical grounds, they originate over a restricted region of the cochlea near the characteristic place of the evoking tone. In support of this view, we previously found good agreement between SFOAE suppression tuning curves (SF-STCs) and a control measure of frequency selectivity (compound action potential suppression tuning curves (CAP-STC)) for frequencies above 3 kHz in chinchillas. For lower frequencies, however, SF-STCs and were over five times broader than the CAP-STCs and demonstrated more high-pass rather than narrow band-pass filter characteristics. Here, we test the hypothesis that the broad tuning of low-frequency SF-STCs is because emissions originate over a broad region of the cochlea extending basal to the characteristic place of the evoking tone. We removed contributions of the hypothesized basally located SFOAE sources by either pre-suppressing them with a high-frequency interference tone (IT; 4.2, 6.2, or 9.2 kHz at 75 dB sound pressure level (SPL)) or by inducing acoustic trauma at high frequencies (exposures to 8, 5, and lastly 3-kHz tones at 110-115 dB SPL). The 1-kHz SF-STCs and CAP-STCs were measured for baseline, IT present and following the acoustic trauma conditions in anesthetized chinchillas. The IT and acoustic trauma affected SF-STCs in an almost indistinguishable way. The SF-STCs changed progressively from a broad high-pass to narrow band-pass shape as the frequency of the IT was lowered and for subsequent exposures to lower-frequency tones. Both results were in agreement with the "basal sources" hypothesis. In contrast, CAP-STCs were not changed by either manipulation, indicating that neither the IT nor acoustic trauma affected the 1-kHz characteristic place. Thus, unlike CAPs, SFOAEs cannot be considered as a place-specific measure of cochlear function at low frequencies, at least in chinchillas.
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Affiliation(s)
- Karolina K Charaziak
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA,
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Patel YA, Butera RJ. Differential fiber-specific block of nerve conduction in mammalian peripheral nerves using kilohertz electrical stimulation. J Neurophysiol 2015; 113:3923-9. [PMID: 25878155 DOI: 10.1152/jn.00529.2014] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 04/13/2015] [Indexed: 11/22/2022] Open
Abstract
Kilohertz electrical stimulation (KES) has been shown to induce repeatable and reversible nerve conduction block in animal models. In this study, we characterized the ability of KES stimuli to selectively block specific components of stimulated nerve activity using in vivo preparations of the rat sciatic and vagus nerves. KES stimuli in the frequency range of 5-70 kHz and amplitudes of 0.1-3.0 mA were applied. Compound action potentials were evoked using either electrical or sensory stimulation, and block of components was assessed through direct nerve recordings and muscle force measurements. Distinct observable components of the compound action potential had unique conduction block thresholds as a function of frequency of KES. The fast component, which includes motor activity, had a monotonically increasing block threshold as a function of the KES frequency. The slow component, which includes sensory activity, showed a nonmonotonic block threshold relationship with increasing KES frequency. The distinct trends with frequency of the two components enabled selective block of one component with an appropriate choice of frequency and amplitude. These trends in threshold of the two components were similar when studying electrical stimulation and responses of the sciatic nerve, electrical stimulation and responses of the vagus nerve, and sensorimotor stimulation and responses of the sciatic nerve. This differential blocking effect of KES on specific fibers can extend the applications of KES conduction block to selective block and stimulation of neural signals for neuromodulation as well as selective control of neural circuits underlying sensorimotor function.
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Affiliation(s)
- Yogi A Patel
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia; Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, Georgia; and
| | - Robert J Butera
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia; School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia
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Sun W, Liu J, Zhang C, Zhou N, Manohar S, Winchester W, Miranda JA, Salvi RJ. Potassium channel activator attenuates salicylate-induced cochlear hearing loss potentially ameliorating tinnitus. Front Neurol 2015; 6:77. [PMID: 25904892 PMCID: PMC4387930 DOI: 10.3389/fneur.2015.00077] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/20/2015] [Indexed: 11/13/2022] Open
Abstract
High dose sodium salicylate causes moderate, reversible hearing loss and tinnitus. Salicylate-induced hearing loss is believed to arise from a reduction in the electromotile response of outer hair cells (OHCs) and/or reduction of KCNQ4 potassium currents in OHCs, which decreases the driving force for the transduction current. Therefore, enhancing OHC potassium currents could potentially prevent salicylate-induced temporary hearing loss. In this study, we tested whether opening voltage-gated potassium channels using ICA-105665, a novel small molecule that opens KCNQ2/3 and KCNQ3/5 channels, can reduce salicylate-induced hearing loss. We found that systemic application of ICA-105665 at 10 mg/kg prevented the salicylate-induced amplitude reduction and threshold shift in the compound action potentials recorded at the round window of the cochlea. ICA-105665 also prevented the salicylate-induced reduction of distortion-product otoacoustic emission. These results suggest that ICA-105665 partially compensates for salicylate-induced cochlear hearing loss by enhancing KCNQ2/3 and KCNQ3/5 potassium currents and the motility of OHCs.
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Affiliation(s)
- Wei Sun
- Center for Hearing and Deafness, State University of New York at Buffalo , Buffalo, NY , USA
| | - Jun Liu
- Department of Otolaryngology, General Hospital of PLA , Beijing , China
| | - Chao Zhang
- Department of Otolaryngology, General Hospital of PLA , Beijing , China
| | - Na Zhou
- Department of Otolaryngology, Peking University Third Hospital , Beijing , China
| | - Senthilvelan Manohar
- Center for Hearing and Deafness, State University of New York at Buffalo , Buffalo, NY , USA
| | | | | | - Richard J Salvi
- Center for Hearing and Deafness, State University of New York at Buffalo , Buffalo, NY , USA
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Ohtsubo S, Fujita T, Matsushita A, Kumamoto E. Inhibition of the compound action potentials of frog sciatic nerves by aroma oil compounds having various chemical structures. Pharmacol Res Perspect 2015; 3:e00127. [PMID: 26038703 PMCID: PMC4448976 DOI: 10.1002/prp2.127] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 01/09/2015] [Accepted: 01/21/2015] [Indexed: 12/12/2022] Open
Abstract
Plant-derived chemicals including aroma oil compounds have an ability to inhibit nerve conduction and modulate transient receptor potential (TRP) channels. Although applying aroma oils to the skin produces a local anesthetic effect, this has not been yet examined throughly. The aim of the present study was to know how nerve conduction inhibitions by aroma oil compounds are related to their chemical structures and whether these activities are mediated by TRP activation. Compound action potentials (CAPs) were recorded from the frog sciatic nerve by using the air-gap method. Citral (aldehyde), which activates various types of TRP channels, attenuated the peak amplitude of CAP with the half-maximal inhibitory concentration (IC50) value of 0.46 mmol/L. Another aldehyde (citronellal), alcohol (citronellol, geraniol, (±)-linalool, (−)-linalool, (+)-borneol, (−)-borneol, α-terpineol), ester (geranyl acetate, linalyl acetate, bornyl acetate), and oxide (rose oxide) compounds also reduced CAP peak amplitudes (IC50: 0.50, 0.35, 0.53, 1.7, 2.0, 1.5, 2.3, 2.7, 0.51, 0.71, 0.44, and 2.6 mmol/L, respectively). On the other hand, the amplitudes were reduced by a small extent by hydrocarbons (myrcene and p-cymene) and ketone (camphor) at high concentrations (2–5 mmol/L). The activities of citral and other TRP agonists ((+)-borneol and camphor) were resistant to TRP antagonist ruthenium red. An efficacy sequence for the CAP inhibitions was generally aldehydes ≥ esters ≥ alcohols > oxides >> hydrocarbons. The CAP inhibition by the aroma oil compound was not related to its octanol–water partition coefficient. It is suggested that aroma oil compounds inhibit nerve conduction in a manner specific to their chemical structures without TRP activation.
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Affiliation(s)
- Sena Ohtsubo
- Department of Physiology, Saga Medical School Saga, Japan
| | - Tsugumi Fujita
- Department of Physiology, Saga Medical School Saga, Japan
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Abstract
OBJECTIVE To determine whether new technology for intraoperative evoked compound action potential (ECAP) threshold measurements-the CR120 Intraoperative Remote Assistant device-is comparable to the existing Custom Sound(®) clinical system, as well as assess test-retest accuracy of the systems. DESIGN Within subject, repeated measures comparative design. STUDY SAMPLE ECAP data were collected from 81 pediatric subjects (41 females and 40 males). RESULTS The average ECAP threshold measurement time for the Custom Sound system was 6.2 minutes (SD = 1.0) versus 4.8 minutes (SD = 0.7) for the CR120 device. ECAP thresholds measured with Custom Sound and the CR120 device had an average Pearson product-moment correlation coefficient for all electrodes (N = 1724) of 0.92, p < 0.01; an average mean absolute difference of 6 CLs (SD = 6); and a 95% confidence interval of - 1 to 1 CLs. The test-retest results for Custom Sound and the CR120 device are also included. CONCLUSION A significant reduction in the measurement time for ECAP thresholds was noted with the CR120 device. Furthermore, ECAP thresholds measured with the CR120 device are equivalent to Custom Sound within a clinically acceptable range.
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Affiliation(s)
- George Tavartkiladze
- * National Research Centre for Audiology and Hearing Rehabilitation , Moscow , Russia
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Mulders WHAM, McMahen C, Robertson D. Effects of chronic furosemide on central neural hyperactivity and cochlear thresholds after cochlear trauma in Guinea pig. Front Neurol 2014; 5:146. [PMID: 25152746 PMCID: PMC4126040 DOI: 10.3389/fneur.2014.00146] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 07/22/2014] [Indexed: 11/16/2022] Open
Abstract
Increased neuronal spontaneous firing rates have been observed throughout the central auditory system after trauma to the cochlea and this hyperactivity is believed to be associated with the phantom perception of tinnitus. Previously, we have shown in an animal model of hearing loss, that an acute injection with furosemide can significantly decrease hyperactivity after cochlear trauma and eliminate behavioral evidence of tinnitus of early onset. However, furosemide also has the potential to affect cochlear thresholds. In this paper, we measured the effects of a chronic (daily injections for 7 days) furosemide treatment on the spontaneous firing rate of inferior colliculus neurons and on cochlear thresholds in order to establish whether a beneficial effect on hyperactivity can be obtained without causing additional hearing loss. Guinea pigs were exposed to a 10–kHz, 124 dB, 2 h acoustic trauma, and after 5 days of recovery, were given daily i.p. injections of 80 mg/kg furosemide or an equivalent amount of saline. The activity of single IC neurons was recorded 24 h following the last injection. The furosemide treatment had no effect on cochlear thresholds compared to saline injections but did result in significant reductions in spontaneous firing rates recorded in inferior colliculus. These results that suggest a long-term beneficial effect of furosemide on hyperactivity after cochlear trauma may be achievable without detrimental effects on hearing, which is important when considering therapeutic potential.
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Affiliation(s)
- Wilhelmina H A M Mulders
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia , Crawley, WA , Australia
| | - Courtney McMahen
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia , Crawley, WA , Australia
| | - Donald Robertson
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia , Crawley, WA , Australia
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Abstract
CONCLUSION Our study demonstrates that the regulation of D2 receptors may be frequency specific. The reduction in cochlear microphonics (CM) and distortion product otoacoustic emission (DPOAE) amplitudes after perfusion with a D2 antagonist suggests that this receptor plays a role in the regulation of cochlear hair cell activation. OBJECTIVES Dopaminergic terminals are subject to negative feedback from dopamine D2 receptors. In the present study we investigated whether the regulation of dopamine D2 receptor is frequency specific and evaluated changes in CM in guinea pig cochlea. METHODS A total of 30 male guinea pigs were randomly assigned to 3 groups and perfused with artificial perilymph (AP), AP containing ethanol (0.1%), or a D2 antagonist (L741626) for 2 h. In each group, compound action potentials (CAPs) evoked by a 1, 2, 4, 8, 16 or 24 kHz tone pip, CM evoked by 4 kHz tone bursts, and DPOAEs were measured before and 2 h after perilymphatic perfusion. RESULTS Perfusion with the D2 antagonist resulted in increased CAP thresholds compared with the other two groups at high frequencies (4, 8, 16, 24 kHz, p < 0.05); however, no significant increase was observed at low frequencies (1, 2 kHz, p > 0.05). There was a significant reduction in DPOAEs and CM amplitudes after the 2 h perfusion with the D2 antagonist. A CM input/output (I/O) function curve plotted with the stimulating level as input and the CM relative amplitude as output indicated obvious nonlinearity after the 2 h perfusion in all three groups.
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Affiliation(s)
- Lin Wang
- Department of Otolaryngology, Peking University People's Hospital , Beijing
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Bourien J, Tang Y, Batrel C, Huet A, Lenoir M, Ladrech S, Desmadryl G, Nouvian R, Puel JL, Wang J. Contribution of auditory nerve fibers to compound action potential of the auditory nerve. J Neurophysiol 2014; 112:1025-39. [PMID: 24848461 DOI: 10.1152/jn.00738.2013] [Citation(s) in RCA: 159] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sound-evoked compound action potential (CAP), which captures the synchronous activation of the auditory nerve fibers (ANFs), is commonly used to probe deafness in experimental and clinical settings. All ANFs are believed to contribute to CAP threshold and amplitude: low sound pressure levels activate the high-spontaneous rate (SR) fibers, and increasing levels gradually recruit medium- and then low-SR fibers. In this study, we quantitatively analyze the contribution of the ANFs to CAP 6 days after 30-min infusion of ouabain into the round window niche. Anatomic examination showed a progressive ablation of ANFs following increasing concentration of ouabain. CAP amplitude and threshold plotted against loss of ANFs revealed three ANF pools: 1) a highly ouabain-sensitive pool, which does not participate in either CAP threshold or amplitude, 2) a less sensitive pool, which only encoded CAP amplitude, and 3) a ouabain-resistant pool, required for CAP threshold and amplitude. Remarkably, distribution of the three pools was similar to the SR-based ANF distribution (low-, medium-, and high-SR fibers), suggesting that the low-SR fiber loss leaves the CAP unaffected. Single-unit recordings from the auditory nerve confirmed this hypothesis and further showed that it is due to the delayed and broad first spike latency distribution of low-SR fibers. In addition to unraveling the neural mechanisms that encode CAP, our computational simulation of an assembly of guinea pig ANFs generalizes and extends our experimental findings to different species of mammals. Altogether, our data demonstrate that substantial ANF loss can coexist with normal hearing threshold and even unchanged CAP amplitude.
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Affiliation(s)
- Jérôme Bourien
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and
| | - Yong Tang
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and Department of Otolaryngology, First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Charlène Batrel
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and
| | - Antoine Huet
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and
| | - Marc Lenoir
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and
| | - Sabine Ladrech
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and
| | - Gilles Desmadryl
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and
| | - Régis Nouvian
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and
| | - Jean-Luc Puel
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and
| | - Jing Wang
- Institut National de la Santé et de la Recherche Médicale UMR 1051, Institute for Neurosciences of Montpellier, Montpellier, France; University of Montpellier 1 and 2, Montpellier, France; and
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Ma M. Role of calpains in the injury-induced dysfunction and degeneration of the mammalian axon. Neurobiol Dis 2013; 60:61-79. [PMID: 23969238 PMCID: PMC3882011 DOI: 10.1016/j.nbd.2013.08.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [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: 03/27/2013] [Revised: 07/17/2013] [Accepted: 08/08/2013] [Indexed: 12/21/2022] Open
Abstract
Axonal injury and degeneration, whether primary or secondary, contribute to the morbidity and mortality seen in many acquired and inherited central nervous system (CNS) and peripheral nervous system (PNS) disorders, such as traumatic brain injury, spinal cord injury, cerebral ischemia, neurodegenerative diseases, and peripheral neuropathies. The calpain family of proteases has been mechanistically linked to the dysfunction and degeneration of axons. While the direct mechanisms by which transection, mechanical strain, ischemia, or complement activation trigger intra-axonal calpain activity are likely different, the downstream effects of unregulated calpain activity may be similar in seemingly disparate diseases. In this review, a brief examination of axonal structure is followed by a focused overview of the calpain family. Finally, the mechanisms by which calpains may disrupt the axonal cytoskeleton, transport, and specialized domains (axon initial segment, nodes, and terminals) are discussed.
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Affiliation(s)
- Marek Ma
- Department of Emergency Medicine, University of Pennsylvania, Philadelphia, PA, USA; Center for Resuscitation Science, University of Pennsylvania, Philadelphia, PA, USA.
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Forgues M, Koehn HA, Dunnon AK, Pulver SH, Buchman CA, Adunka OF, Fitzpatrick DC. Distinguishing hair cell from neural potentials recorded at the round window. J Neurophysiol 2013; 111:580-93. [PMID: 24133227 DOI: 10.1152/jn.00446.2013] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Almost all patients who receive cochlear implants have some acoustic hearing prior to surgery. Electrocochleography (ECoG), or electrophysiological measures of cochlear response to sound, can identify remaining auditory nerve activity that is the basis for this residual hearing and can record potentials from hair cells that are no longer functionally connected to nerve fibers. The ECoG signal is therefore complex, being composed of both hair cell and neural signals. To identify signatures of different sources in the recorded potentials, we collected ECoG data across frequency and intensity from the round window of gerbils before and after treatment with kainic acid, a neurotoxin. Distortions in the recorded waveforms were produced by different sources over different ranges of frequency and intensity. In response to tones at low frequencies and low-to-moderate intensities, the major source of distortion was from neural phase-locking that was sensitive to kainic acid. At high intensities at all frequencies, the distortion was not sensitive to kainic acid and was consistent with asymmetric saturation of the hair cell transducer current. In addition to loss of phase-locking, changes in the envelope after kainic acid treatment indicate that sustained neural firing combines with receptor potentials from hair cells to produce the envelope of the response to tones. These results provide baseline data to interpret comparable recordings from human cochlear implant recipients.
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Affiliation(s)
- Mathieu Forgues
- Department of Otolaryngology/Head and Neck Surgery, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Brown DJ, Chihara Y, Wang Y. Changes in utricular function during artificial endolymph injections in guinea pigs. Hear Res 2013; 304:70-6. [PMID: 23792075 DOI: 10.1016/j.heares.2013.05.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/07/2013] [Accepted: 05/27/2013] [Indexed: 01/13/2023]
Abstract
Various theories suggest endolymphatic hydrops may cause a rupture of the membranous labyrinth or may force open the utriculo-saccular duct, resulting in a sudden change in inner ear function. Here, we have used slow injections of artificial endolymph into either scala media or the utricle of anaesthetised guinea pigs to investigate the effects of hydrops. Vestibular function was continuously monitored in addition to the measurements of cochlear function developed in our laboratory (Brown et al. Hear Res, 2013). Scala media injection induced consistent functional changes, which occurred in two stages. Initial changes involved were associated with an increased hydrostatic pressure in scala media that only affected cochlear function. After 3-4 μl of endolymph had been injected, cochlear function spontaneously recovered, and was often shortly followed by a transient increase or decrease in utricular sensitivity, with the effects varying between animals. Endolymph injection directly into the utricle produced variable effects across animals, although in 2 experiments it produced similar changes as those observed for scala media injections, suggesting that the fluid pathway between scala media and the utricle was continuous in these animals. The mechanism underlying the sudden, spontaneous functional changes is not yet clear, but we tentatively suggest that in some cases it may be caused by the utriculo-saccular duct suddenly opening to alleviate an elevated hydrostatic pressure in the pars inferior, resulting in a change in utricular function due to an increase in its volume. These changes are comparable to the sudden or fluctuating functional changes in Ménière's sufferers, and support the hypothesis that endolymphatic hydrops can directly cause some symptoms of this syndrome.
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Affiliation(s)
- D J Brown
- The Brain and Mind Research Institute, Sydney Medical School, The University of Sydney, 100 Mallett Street, Camperdown 2050, Australia.
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Abstract
OBJECTIVES Presently available nonbehavioral methods to estimate auditory thresholds perform less well at frequencies below 1 kHz than at 1 kHz and above. For many uses, such as providing accurate infant hearing aid amplification for low-frequency vowels, an accurate nonbehavioral method to estimate low-frequency thresholds is needed. A novel technique was developed to estimate low-frequency cochlear thresholds based on the use of a previously reported waveform. It was determined how well the method worked by comparing the resulting thresholds to thresholds from onset-response compound action potentials (CAPs) and single-auditory-nerve (AN)- fibers in cats. A long-term goal is to translate this technique for use in humans. DESIGN An electrode near the cochlea records a combination of cochlear microphonic (CM) and neural responses. In response to low-frequency, near threshold-level tones, the CM is almost sinusoidal whereas the neural responses occur preferentially at one phase of the tone. If the tone is presented again but with its polarity reversed, the neural response keeps the same shape, but shifts ½ cycle in time. Averaging responses to tones presented separately at opposite polarities overlaps and interleaves the neural responses and yields a waveform in which the CM is canceled and the neural response appears twice each tone cycle, that is, the resulting neural response is mostly at twice the tone frequency. The resultant waveform is referred to as "the auditory nerve overlapped waveform" (ANOW). In this study, ANOW level functions were measured in anesthetized cats from 10 to 80 dB SPL in 10 dB steps using tones between 0.3 and 1 kHz. As a response metric, the magnitude of the ANOW component was calculated at twice the tone frequency (ANOW2f). The ANOW threshold was the sound level where the interpolated ANOW2f crossed a statistical criterion that was higher than 95% of the noise floor distribution. ANOW thresholds were compared with onset-CAP thresholds from the same recordings and single-AN-fiber thresholds from the same animals. RESULTS ANOW and onset-CAP level functions were obtained for 0.3 to 1 kHz tones, and single-AN-fiber responses from cats. Except at 1 kHz, typical ANOW thresholds were mostly 10 to 20 dB more sensitive than onset-CAP thresholds and 10 to 20 dB less sensitive than the most sensitive single-AN-fiber thresholds. CONCLUSIONS ANOW provides frequency-specific estimates of cochlear neural thresholds over a frequency range that is important for hearing but is not well accessed by nonbehavioral, objective methods. Results suggest that with further targeted development, the ANOW low-frequency threshold estimation technique can be useful both clinically in humans and in basic-science animal experiments.
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Affiliation(s)
- Jeffery T Lichtenhan
- Massachusetts Eye & Ear Infirmary, Eaton-Peabody Laboratory of Auditory Physiology, Boston, MA 02114, USA.
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Duke AR, Cayce JM, Malphrus JD, Konrad P, Mahadevan-Jansen A, Jansen ED. Combined optical and electrical stimulation of neural tissue in vivo. J Biomed Opt 2009; 14:060501. [PMID: 20059232 PMCID: PMC2789115 DOI: 10.1117/1.3257230] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 08/13/2009] [Accepted: 09/08/2009] [Indexed: 05/25/2023]
Abstract
Low-intensity, pulsed infrared light provides a novel nerve stimulation modality that avoids the limitations of traditional electrical methods such as necessity of contact, presence of a stimulation artifact, and relatively poor spatial precision. Infrared neural stimulation (INS) is, however, limited by a 2:1 ratio of threshold radiant exposures for damage to that for stimulation. We have shown that this ratio is increased to nearly 6:1 by combining the infrared pulse with a subthreshold electrical stimulus. Our results indicate a nonlinear relationship between the subthreshold depolarizing electrical stimulus and additional optical energy required to reach stimulation threshold. The change in optical threshold decreases linearly as the delay between the electrical and optical pulses is increased. We have shown that the high spatial precision of INS is maintained for this combined stimulation modality. Results of this study will facilitate the development of applications for infrared neural stimulation, as well as target the efforts to uncover the mechanism by which infrared light activates neural tissue.
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Le Prell CG, Halsey K, Hughes LF, Dolan DF, Bledsoe SC. Disruption of lateral olivocochlear neurons via a dopaminergic neurotoxin depresses sound-evoked auditory nerve activity. J Assoc Res Otolaryngol 2005; 6:48-62. [PMID: 15735934 PMCID: PMC2504639 DOI: 10.1007/s10162-004-5009-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [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: 01/30/2004] [Accepted: 10/29/2004] [Indexed: 11/30/2022] Open
Abstract
We applied the dopaminergic (DA) neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to the guinea pig cochlear perilymph. Immunolabeling of lateral olivocochlear (LOC) neurons using antibodies against synaptophysin was reduced after the MPTP treatment. In contrast, labeling of the medial olivocochlear innervation remained intact. As after brainstem lesions of the lateral superior olive (LSO), the site of origin of the LOC neurons, the main effect of disrupting LOC innervation of the cochlea via MPTP was a depression of the amplitude of the compound action potential (CAP). CAP amplitude depression was similar to that produced by LSO lesions. Latency of the N1 component of the CAP, and distortion product otoacoustic emission amplitude and adaptation were unchanged by the MPTP treatment. This technique for selectively lesioning descending LOC efferents provides a new opportunity for examining LOC modulation of afferent activity and behavioral measures of perception.
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MESH Headings
- 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/pharmacology
- Action Potentials
- Adaptation, Physiological/drug effects
- Adaptation, Physiological/physiology
- Animals
- Cochlear Nerve/physiology
- Cochlear Nucleus/pathology
- Cochlear Nucleus/physiology
- Denervation
- Dopamine/physiology
- Dopamine Agents/pharmacology
- Evoked Potentials, Auditory, Brain Stem/drug effects
- Evoked Potentials, Auditory, Brain Stem/physiology
- Female
- Guinea Pigs
- Immunohistochemistry
- Male
- Neurotoxins/pharmacology
- Olivary Nucleus/pathology
- Olivary Nucleus/physiology
- Otoacoustic Emissions, Spontaneous/drug effects
- Otoacoustic Emissions, Spontaneous/physiology
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Affiliation(s)
- Colleen G Le Prell
- Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, MI 48109-0506, USA.
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Le Prell CG, Shore SE, Hughes LF, Bledsoe SC. Disruption of lateral efferent pathways: functional changes in auditory evoked responses. J Assoc Res Otolaryngol 2003; 4:276-90. [PMID: 12943378 PMCID: PMC3202720 DOI: 10.1007/s10162-002-3018-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [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: 04/24/2002] [Accepted: 11/13/2002] [Indexed: 10/26/2022] Open
Abstract
The functional consequences of selectively lesioning the lateral olivocochlear efferent system in guinea pigs were studied. The lateral superior olive (LSO) contains the cell bodies of lateral olivocochlear neurons. Melittin, a cytotoxic chemical, was injected into the brain stem using stereotaxic coordinates and near-field evoked potentials to target the LSO. Brain stem histology revealed discrete damage to the LSO following the injections. Functional consequences of this damage were reflected in depressed amplitude of the compound action potential of the eighth nerve (CAP) following the lesion. Threshold sensitivity and N1 latencies were relatively unchanged. Onset adaptation of the cubic distortion product otoacoustic emission (DPOAE) was evident, suggesting a reasonably intact medial efferent system. The present results provide the first report of functional changes induced by isolated manipulation of the lateral efferent pathway. They also confirm the suggestion that changes in single-unit auditory nerve activity after cutting the olivocochlear bundle are probably a consequence of disrupting the more lateral of the two olivocochlear efferent pathways.
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Affiliation(s)
- Colleen G Le Prell
- Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, MI 48109-0506, USA.
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Tekkök SB, Goldberg MP. Ampa/kainate receptor activation mediates hypoxic oligodendrocyte death and axonal injury in cerebral white matter. J Neurosci 2001; 21:4237-48. [PMID: 11404409 PMCID: PMC6762765] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Abstract
We developed an in situ model to investigate the hypothesis that AMPA/kainate (AMPA/KA) receptor activation contributes to hypoxic-ischemic white matter injury in the adult brain. Acute coronal brain slices, including corpus callosum, were prepared from adult mice. After exposure to transient oxygen and glucose deprivation (OGD), white matter injury was assessed by electrophysiology and immunofluorescence for oligodendrocytes and axonal neurofilaments. White matter cellular components and the stimulus-evoked compound action potential (CAP) remained stable for 12 hr after preparation. OGD for 30 min resulted in an irreversible loss of the CAP as well as structural disruption of axons and subsequent loss of neurofilament immunofluorescence. OGD also caused widespread oligodendrocyte death, demonstrated by the loss of APC labeling and the gain of pyknotic nuclear morphology and propidium iodide labeling. Blockade of AMPA/KA receptors with 30 microm NBQX or the AMPA-selective antagonist 30 microm GYKI 52466 prevented OGD-induced oligodendrocyte death. Oligodendrocytes also were preserved by the removal of Ca(2+), but not by a blockade of voltage-gated Na(+) channels. The protective action of NBQX was still present in isolated corpus callosum slices. CAP areas and axonal structure were preserved by Ca(2+) removal and partially protected by a blockade of voltage-gated Na(+) channels. NBQX prevented OGD-induced CAP loss and preserved axonal structure. These observations highlight convergent pathways leading to hypoxic-ischemic damage of cerebral white matter. In accordance with previous suggestions, the activation of voltage-gated Na(+) channels contributes to axonal damage. Overactivation of glial AMPA/KA receptors leads to oligodendrocyte death and also plays an important role in structural and functional disruption of axons.
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Affiliation(s)
- S B Tekkök
- Department of Neurology, Center for the Study of Nervous System Injury, Washington University, St. Louis, Missouri 63110-1193, USA
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Zhong J, Dietzel ID, Wahle P, Kopf M, Heumann R. Sensory impairments and delayed regeneration of sensory axons in interleukin-6-deficient mice. J Neurosci 1999; 19:4305-13. [PMID: 10341234 PMCID: PMC6782624] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Abstract
Interleukin-6 (IL-6) is a multifunctional cytokine mediating inflammatory or immune reactions. Here we investigated the possible role of IL-6 in the intact or lesioned peripheral nervous system using adult IL-6 gene knockout (IL-6(-/-)) mice. Various sensory functions were tested by applying electrophysiological, morphological, biochemical, and behavioral methods. There was a 60% reduction of the compound action potential of the sensory branch of IL-6(-/-) mice as compared with the motor branch in the intact sciatic nerve. Cross sections of L5 DRG of IL-6(-/-) mice showed a shift in the relative size distribution of the neurons. The temperature sensitivity of IL-6(-/-) mice was also significantly reduced. After crush lesion of the sciatic nerve, its functional recovery was delayed in IL-6(-/-) mice as analyzed from a behavioral footprint assay. Measurements of compound action potentials 20 d after crush lesion showed that there was a very low level of recovery of the sensory but not of the motor branch of IL-6(-/-) mice. Similar results of sensory impairments were obtained with mice showing slow Wallerian degeneration (Wlds) and a delayed lesion-induced recruitment of macrophages. However, in contrast to WldS mice, in IL-6(-/-) mice we observed the characteristic lesion-induced invasion of macrophages and the upregulation of low-affinity neurotrophin receptor p75 (p75LNTR) mRNA levels identical to those of IL-6(+/+) mice. Thus, the mechanisms leading to the common sensory deficiencies were different between IL-6(-/-) and WldS mice. Altogether, the results suggest that interleukin-6 is essential to modulate sensory functions in vivo.
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Affiliation(s)
- J Zhong
- Lehrstuhl für Molekulare Neurobiochemie, Ruhr-Universität Bochum, 44780 Bochum Germany
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Lee Y, López DE, Meloni EG, Davis M. A primary acoustic startle pathway: obligatory role of cochlear root neurons and the nucleus reticularis pontis caudalis. J Neurosci 1996; 16:3775-89. [PMID: 8642420 PMCID: PMC6578836] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Davis et al. (1982) proposed a primary acoustic startle circuit in rats consisting of the auditory nerve, posteroventral cochlear nucleus, an area near the ventrolateral lemniscus (VLL), nucleus reticularis pontis caudalis (PnC), and spinal motoneurons. Using fiber-sparing lesions, the present study reevaluated these and other structures together with the role of neurons embedded in the auditory nerve [cochlear root neurons (CRNs)], recently hypothesized to be involved in acoustic startle. Small electrolytic lesions of the VLL of ventrolateral tegmental nucleus (VLTg) failed to eliminate startle. Large electrolytic lesions including the rostral ventral nucleus of the trapezoid body (rVNTB) and ventrolateral parts of PnC or lesions of the entire PnC blocked startle. However, small NMDA-induced lesions of the rVNTB failed to block startle, making it unlikely that the rVNTB itself is part of the startle pathway. In contrast, NMDA lesions of the full extension of the ventrolateral part of the PnC blocked startle completely, suggesting that the ventrolateral part of the PnC is critically involved. Bilateral kainic acid lesions of CRNs also blocked the startle reflex completely, providing the first direct evidence for an involvement of CRNs in startle. This blockade probably was not caused by damage to the auditory nerve, because the lesioned animals showed intact compound action potentials recorded from the ventral cochlear nucleus. Hence, a primary acoustic startle pathway may involve three synapses onto (1) CRNs, (2) neurons in PnC, and (3) spinal motoneurons.
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Affiliation(s)
- Y Lee
- Yale University School of Medicine, Connecticut Mental Health Center, New Haven 06508, USA
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May BJ, McQuone SJ. Effects of Bilateral Olivocochlear Lesions on Pure-Tone Intensity Discrimination in Cats. Audit Neurosci 1995; 1:385-400. [PMID: 23814451 PMCID: PMC3695712] [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] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Behavioral experiments examined the effects of olivocochlear efferent lesions on performance in an intensity discrimination task. Five cats were trained with food reinforcement to signal the detection of a change in the intensity of pure tones by releasing a response lever. Intensity cues were conveyed by 1 and 8-kHz tone bursts in quiet and in the presence of continuous broadband noise. After the collection of baseline behavioral data, the olivocochlear bundle (OCB) was sectioned with bilateral knife cuts on the floor of the IVth ventricle. The completeness of OCB lesions was evaluated at the conclusion of post-lesion behavioral testing by light microscopic examination of cochlear acetylcholinesterase staining and electrophysiological measures of contralateral noise suppression of compound action potentials (CAPs). Cats with OCB lesions showed greatest performance deficits for the discrimination of 8-kHz intensity changes in continuous background noise. The subjects' ability to discriminate 1-kHz intensity changes in noise was poor prior to OCB lesioning and did not change after the surgical procedure. Lesioning effects were not observed at either frequency when tests were conducted in quiet. These results suggest that olivocochlear feedback contributes to the auditory processing of mid-frequency acoustic signals in noisy backgrounds.
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Affiliation(s)
- Bradford J May
- Department of Otolaryngology-HNS, Center for Hearing and Balance, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
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