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Kim YH, Schrode KM, Engel J, Vicencio-Jimenez S, Rodriguez G, Lee HK, Lauer AM. Auditory Behavior in Adult-Blinded Mice. J Assoc Res Otolaryngol 2022; 23:225-239. [PMID: 35084628 PMCID: PMC8964904 DOI: 10.1007/s10162-022-00835-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/31/2021] [Indexed: 10/19/2022] Open
Abstract
Cross-modal plasticity occurs when the function of remaining senses is enhanced following deprivation or loss of a sensory modality. Auditory neural responses are enhanced in the auditory cortex, including increased sensitivity and frequency selectivity, following short-term visual deprivation in adult mice (Petrus et al. Neuron 81:664-673, 2014). Whether or not these visual deprivation-induced neural changes translate into improved auditory perception and performance remains unclear. As an initial investigation of the effects of adult visual deprivation on auditory behaviors, CBA/CaJ mice underwent binocular enucleation at 3-4 weeks old and were tested on a battery of learned behavioral tasks, acoustic startle response (ASR), and prepulse inhibition (PPI) tests beginning at least 2 weeks after the enucleation procedure. Auditory brain stem responses (ABRs) were also measured to screen for potential effects of visual deprivation on non-behavioral hearing function. Control and enucleated mice showed similar tone detection sensitivity and frequency discrimination in a conditioned lick suppression test. Both groups showed normal reactivity to sound as measured by ASR in a quiet background. However, when startle-eliciting stimuli were presented in noise, enucleated mice showed decreased ASR amplitude relative to controls. Control and enucleated mice displayed no significant differences in ASR habituation, PPI tests, or ABR thresholds, or wave morphology. Our findings suggest that while adult-onset visual deprivation induces cross-modal plasticity at the synaptic and circuit levels, it does not substantially influence simple auditory behavioral performance.
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Affiliation(s)
- Ye-Hyun Kim
- Department of Otolaryngology-Head and Neck Surgery and Center for Hearing and Balance, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Katrina M Schrode
- Department of Otolaryngology-Head and Neck Surgery and Center for Hearing and Balance, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - James Engel
- Department of Otolaryngology-Head and Neck Surgery and Center for Hearing and Balance, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Sergio Vicencio-Jimenez
- Department of Otolaryngology-Head and Neck Surgery and Center for Hearing and Balance, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Gabriela Rodriguez
- Cell, Molecular, Developmental Biology, and Biophysics (CMDB) Graduate Program, Johns Hopkins University, Baltimore, MD, USA
| | - Hey-Kyoung Lee
- Cell, Molecular, Developmental Biology, and Biophysics (CMDB) Graduate Program, Johns Hopkins University, Baltimore, MD, USA.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.,Zanvyl-Krieger Mind/Brain Institute and Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Amanda M Lauer
- Department of Otolaryngology-Head and Neck Surgery and Center for Hearing and Balance, Johns Hopkins University, Baltimore, MD, 21205, USA. .,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
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Lauer AM, Behrens D, Klump G. Acoustic startle modification as a tool for evaluating auditory function of the mouse: Progress, pitfalls, and potential. Neurosci Biobehav Rev 2017; 77:194-208. [PMID: 28327385 PMCID: PMC5446932 DOI: 10.1016/j.neubiorev.2017.03.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/23/2017] [Accepted: 03/13/2017] [Indexed: 12/16/2022]
Abstract
Acoustic startle response (ASR) modification procedures, especially prepulse inhibition (PPI), are increasingly used as behavioral measures of auditory processing and sensorimotor gating in rodents due to their perceived ease of implementation and short testing times. In practice, ASR and PPI procedures are extremely variable across animals, experimental setups, and studies, and the interpretation of results is subject to numerous caveats and confounding influences. We review considerations for modification of the ASR using acoustic stimuli, and we compare the sensitivity of PPI procedures to more traditional operant psychoacoustic techniques. We also discuss non-auditory variables that must be considered. We conclude that ASR and PPI measures cannot substitute for traditional operant techniques due to their low sensitivity. Additionally, a substantial amount of pilot testing must be performed to properly optimize an ASR modification experiment, negating any time benefit over operant conditioning. Nevertheless, there are some circumstances where ASR measures may be the only option for assessing auditory behavior, such as when testing mouse strains with early-onset hearing loss or learning impairments.
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Affiliation(s)
- Amanda M Lauer
- Department of Otolaryngology-Head and Neck Surgery and Center for Hearing and Balance, Johns Hopkins University, 515 Traylor Building, 720 Rutland Ave., Baltimore, MD 21205, USA.
| | - Derik Behrens
- Cluster of Excellence Hearing4all, Animal Physiology & Behavior Group, Department for Neuroscience, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, Carl Von Ossietzky Str. 9-11, 26111 Oldenburg, Germany
| | - Georg Klump
- Cluster of Excellence Hearing4all, Animal Physiology & Behavior Group, Department for Neuroscience, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, Carl Von Ossietzky Str. 9-11, 26111 Oldenburg, Germany
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3
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Fournier P, Hébert S. The gap-startle paradigm to assess auditory temporal processing: Bridging animal and human research. Psychophysiology 2016; 53:759-66. [PMID: 26841102 DOI: 10.1111/psyp.12620] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 12/09/2015] [Indexed: 11/25/2022]
Abstract
The gap-prepulse inhibition of the acoustic startle (GPIAS) paradigm is the primary test used in animal research to identify gap detection thresholds and impairment. When a silent gap is presented shortly before a loud startling stimulus, the startle reflex is inhibited and the extent of inhibition is assumed to reflect detection. Here, we applied the same paradigm in humans. One hundred and fifty-seven normal-hearing participants were tested using one of five gap durations (5, 25, 50, 100, 200 ms) in one of the following two paradigms-gap-embedded in or gap-following-the continuous background noise. The duration-inhibition relationship was observable for both conditions but followed different patterns. In the gap-embedded paradigm, GPIAS increased significantly with gap duration up to 50 ms and then more slowly up to 200 ms (trend only). In contrast, in the gap-following paradigm, significant inhibition-different from 0--was observable only at gap durations from 50 to 200 ms. The finding that different patterns are found depending on gap position within the background noise is compatible with distinct mechanisms underlying each of the two paradigms.
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Affiliation(s)
- Philippe Fournier
- École d'orthophonie et d'audiologie, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada.,BRAMS, International Laboratory for Brain, Music, and Sound Research, Université de Montréal and McGill University, Montréal, Québec, Canada.,Centre de recherche, Institut universitaire de gériatrie de Montréal, Montréal, Québec, Canada
| | - Sylvie Hébert
- École d'orthophonie et d'audiologie, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada.,BRAMS, International Laboratory for Brain, Music, and Sound Research, Université de Montréal and McGill University, Montréal, Québec, Canada.,Centre de recherche, Institut universitaire de gériatrie de Montréal, Montréal, Québec, Canada
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4
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Altschuler RA, Dolan DF, Halsey K, Kanicki A, Deng N, Martin C, Eberle J, Kohrman DC, Miller RA, Schacht J. Age-related changes in auditory nerve-inner hair cell connections, hair cell numbers, auditory brain stem response and gap detection in UM-HET4 mice. Neuroscience 2015; 292:22-33. [PMID: 25665752 DOI: 10.1016/j.neuroscience.2015.01.068] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 01/12/2015] [Accepted: 01/29/2015] [Indexed: 01/24/2023]
Abstract
This study compared the timing of appearance of three components of age-related hearing loss that determine the pattern and severity of presbycusis: the functional and structural pathologies of sensory cells and neurons and changes in gap detection (GD), the latter as an indicator of auditory temporal processing. Using UM-HET4 mice, genetically heterogeneous mice derived from four inbred strains, we studied the integrity of inner and outer hair cells by position along the cochlear spiral, inner hair cell-auditory nerve connections, spiral ganglion neurons (SGN), and determined auditory thresholds, as well as pre-pulse and gap inhibition of the acoustic startle reflex (ASR). Comparisons were made between mice of 5-7, 22-24 and 27-29 months of age. There was individual variability among mice in the onset and extent of age-related auditory pathology. At 22-24 months of age a moderate to large loss of outer hair cells was restricted to the apical third of the cochlea and threshold shifts in the auditory brain stem response were minimal. There was also a large and significant loss of inner hair cell-auditory nerve connections and a significant reduction in GD. The expression of Ntf3 in the cochlea was significantly reduced. At 27-29 months of age there was no further change in the mean number of synaptic connections per inner hair cell or in GD, but a moderate to large loss of outer hair cells was found across all cochlear turns as well as significantly increased ABR threshold shifts at 4, 12, 24 and 48 kHz. A statistical analysis of correlations on an individual animal basis revealed that neither the hair cell loss nor the ABR threshold shifts correlated with loss of GD or with the loss of connections, consistent with independent pathological mechanisms.
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Affiliation(s)
- R A Altschuler
- Kresge Hearing Research Institute, Dept. of Otolaryngology, University of Michigan, Ann Arbor, MI, USA; Dept. of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - D F Dolan
- Kresge Hearing Research Institute, Dept. of Otolaryngology, University of Michigan, Ann Arbor, MI, USA
| | - K Halsey
- Kresge Hearing Research Institute, Dept. of Otolaryngology, University of Michigan, Ann Arbor, MI, USA
| | - A Kanicki
- Kresge Hearing Research Institute, Dept. of Otolaryngology, University of Michigan, Ann Arbor, MI, USA
| | - N Deng
- Kresge Hearing Research Institute, Dept. of Otolaryngology, University of Michigan, Ann Arbor, MI, USA
| | - C Martin
- Kresge Hearing Research Institute, Dept. of Otolaryngology, University of Michigan, Ann Arbor, MI, USA
| | - J Eberle
- Kresge Hearing Research Institute, Dept. of Otolaryngology, University of Michigan, Ann Arbor, MI, USA
| | - D C Kohrman
- Kresge Hearing Research Institute, Dept. of Otolaryngology, University of Michigan, Ann Arbor, MI, USA; Dept. of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - R A Miller
- Dept. of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - J Schacht
- Kresge Hearing Research Institute, Dept. of Otolaryngology, University of Michigan, Ann Arbor, MI, USA
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Hartley DEH, Isaiah A. Envelope enhancement increases cortical sensitivity to interaural envelope delays with acoustic and electric hearing. PLoS One 2014; 9:e104097. [PMID: 25093417 PMCID: PMC4122409 DOI: 10.1371/journal.pone.0104097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 07/10/2014] [Indexed: 11/20/2022] Open
Abstract
Evidence from human psychophysical and animal electrophysiological studies suggests that sensitivity to interaural time delay (ITD) in the modulating envelope of a high-frequency carrier can be enhanced using half-wave rectified stimuli. Recent evidence has shown potential benefits of equivalent electrical stimuli to deaf individuals with bilateral cochlear implants (CIs). In the current study we assessed the effects of envelope shape on ITD sensitivity in the primary auditory cortex of normal-hearing ferrets, and profoundly-deaf animals with bilateral CIs. In normal-hearing animals, cortical sensitivity to ITDs (±1 ms in 0.1-ms steps) was assessed in response to dichotically-presented i) sinusoidal amplitude-modulated (SAM) and ii) half-wave rectified (HWR) tones (100-ms duration; 70 dB SPL) presented at the best-frequency of the unit over a range of modulation frequencies. In separate experiments, adult ferrets were deafened with neomycin administration and bilaterally-implanted with intra-cochlear electrode arrays. Electrically-evoked auditory brainstem responses (EABRs) were recorded in response to bipolar electrical stimulation of the apical pair of electrodes with singe biphasic current pulses (40 µs per phase) over a range of current levels to measure hearing thresholds. Subsequently, we recorded cortical sensitivity to ITDs (±800 µs in 80-µs steps) within the envelope of SAM and HWR biphasic-pulse trains (40 µs per phase; 6000 pulses per second, 100-ms duration) over a range of modulation frequencies. In normal-hearing animals, nearly a third of cortical neurons were sensitive to envelope-ITDs in response to SAM tones. In deaf animals with bilateral CI, the proportion of ITD-sensitive cortical neurons was approximately a fifth in response to SAM pulse trains. In normal-hearing and deaf animals with bilateral CI the proportion of ITD sensitive units and neural sensitivity to ITDs increased in response to HWR, compared with SAM stimuli. Consequently, novel stimulation strategies based on envelope enhancement may prove beneficial to individuals with bilateral cochlear implants.
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Affiliation(s)
- Douglas E. H. Hartley
- NIHR National Biomedical Research Unit in Hearing, Ropewalk House, Nottingham, United Kingdom
- Department of Otolaryngology, School of Clinical Sciences, Nottingham University, Nottingham, United Kingdom
- Medical Research Council Institute of Hearing Research, University Park, Nottingham, United Kingdom
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Amal Isaiah
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
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6
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Abstract
AbstractOffset neurons which respond to the termination of the sound stimulation may play important roles in auditory temporal information processing, sound signal recognition, and complex distinction. Two additional possible mechanisms were reviewed: neural inhibition and the intrinsic conductance property of offset neuron membranes. The underlying offset response was postulated to be located in the superior paraolivary nucleus of mice. The biological significance of the offset neurons was discussed as well.
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7
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Abstract
Neural slowing is commonly noted in older adults, with consequences for sensory, motor, and cognitive domains. One of the deleterious effects of neural slowing is impairment of temporal resolution; older adults, therefore, have reduced ability to process the rapid events that characterize speech, especially in noisy environments. Although hearing aids provide increased audibility, they cannot compensate for deficits in auditory temporal processing. Auditory training may provide a strategy to address these deficits. To that end, we evaluated the effects of auditory-based cognitive training on the temporal precision of subcortical processing of speech in noise. After training, older adults exhibited faster neural timing and experienced gains in memory, speed of processing, and speech-in-noise perception, whereas a matched control group showed no changes. Training was also associated with decreased variability of brainstem response peaks, suggesting a decrease in temporal jitter in response to a speech signal. These results demonstrate that auditory-based cognitive training can partially restore age-related deficits in temporal processing in the brain; this plasticity in turn promotes better cognitive and perceptual skills.
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8
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Deficits in responding to brief noise offsets in Kcna1 -/- mice reveal a contribution of this gene to precise temporal processing seen previously only for stimulus onsets. J Assoc Res Otolaryngol 2012; 13:351-8. [PMID: 22302114 DOI: 10.1007/s10162-011-0312-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 12/25/2011] [Indexed: 10/14/2022] Open
Abstract
The voltage-gated potassium channel subunit Kv1.1 encoded by the Kcna1 gene is expressed in many brainstem nuclei, and electrophysiological studies of Kcna1-null mutant (-/-) single neurons suggest that channels containing this subunit are critical for precise processing of rapid acoustic perturbations. We tested the hypothesis that brief offsets of a background noise are behaviorally less salient for Kcna1 -/- mice, measured by changes in noise offset inhibition of acoustic startle reflexes (ASR). In experiment 1, noise offset was followed by ASR-eliciting sound bursts either after 1-10 ms quiet intervals or after the return of noise for 10-290 ms following 10-ms quiet gaps. ASR inhibition to offset and gaps was initially higher in +/+ mice but persisted longer in -/- mice. Experiment 2 contrasted brief abrupt offsets with ramped offsets of the same duration up to 10 ms, the ramps intended to simulate progressively slower internal decays of afferent processing. Both groups had greater inhibition for abrupt offsets at asymptote, and this difference was evident at the 1-ms interval in +/+ but not -/- mice. Further, the asymptotic effect of ramped offsets in +/+ mice was equal to that produced by abrupt offsets in null mutants, suggesting more perseveration of internal afferent activity following noise offset in -/- mice. Overall, these data are consistent with prior electrophysiological studies showing that the neural mechanisms for processing acoustic transients are less effective in Kcna1 -/- mice and support previous proposals that Kv1.1 contributes to the perception of animal vocalizations and human speech.
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Gourévitch B, Edeline JM. Age-related changes in the guinea pig auditory cortex: relationship with brainstem changes and comparison with tone-induced hearing loss. Eur J Neurosci 2011; 34:1953-65. [DOI: 10.1111/j.1460-9568.2011.07905.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hartley DEH, Dahmen JC, King AJ, Schnupp JWH. Binaural sensitivity changes between cortical on and off responses. J Neurophysiol 2011; 106:30-43. [PMID: 21562191 DOI: 10.1152/jn.01070.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neurons exhibiting on and off responses with different frequency tuning have previously been described in the primary auditory cortex (A1) of anesthetized and awake animals, but it is unknown whether other tuning properties, including sensitivity to binaural localization cues, also differ between on and off responses. We measured the sensitivity of A1 neurons in anesthetized ferrets to 1) interaural level differences (ILDs), using unmodulated broadband noise with varying ILDs and average binaural levels, and 2) interaural time delays (ITDs), using sinusoidally amplitude-modulated broadband noise with varying envelope ITDs. We also assessed fine-structure ITD sensitivity and frequency tuning, using pure-tone stimuli. Neurons most commonly responded to stimulus onset only, but purely off responses and on-off responses were also recorded. Of the units exhibiting significant binaural sensitivity nearly one-quarter showed binaural sensitivity in both on and off responses, but in almost all (∼97%) of these units the binaural tuning of the on responses differed significantly from that seen in the off responses. Moreover, averaged, normalized ILD and ITD tuning curves calculated from all units showing significant sensitivity to binaural cues indicated that on and off responses displayed different sensitivity patterns across the population. A principal component analysis of ITD response functions suggested a continuous cortical distribution of binaural sensitivity, rather than discrete response classes. Rather than reflecting a release from inhibition without any functional significance, we propose that binaural off responses may be important to cortical encoding of sound-source location.
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Affiliation(s)
- Douglas E H Hartley
- Department of Physiology, Anatomy, and Genetics, Oxford University, Oxford, United Kingdom.
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11
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Lauer AM, May BJ. The medial olivocochlear system attenuates the developmental impact of early noise exposure. J Assoc Res Otolaryngol 2011; 12:329-43. [PMID: 21347798 DOI: 10.1007/s10162-011-0262-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Accepted: 02/07/2011] [Indexed: 10/18/2022] Open
Abstract
The early onset of peripheral deafness profoundly alters the functional maturation of the central auditory system. A prolonged exposure to an artificial acoustic environment has a similar disruptive influence. These observations establish the importance of normal patterns of sound-driven activity during the initial stages of auditory development. The present study was designed to address the role of cochlear gain control during these activity-dependent developmental processes. It was hypothesized that the regulation of auditory nerve activity by the medial olivocochlear system (MOCS) would preserve normal development when the immature auditory system was challenged by continuous background noise. To test this hypothesis, knock-out mice lacking MOCS feedback were reared in noisy or quiet environments and then evaluated with behavioral paradigms for auditory processing deficits. Relative to wild-type controls, noise-reared knock-out mice showed a decreased ability to process rapid acoustic events. Additional anatomical and physiological assessments linked these perceptual deficits to synaptic defects in the auditory brainstem that shared important features with human auditory neuropathy. Our findings offer a new perspective on the potentially damaging effects of environmental noise and how these risks are ameliorated by the protective role of MOCS feedback.
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Affiliation(s)
- Amanda M Lauer
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD 21205, USA.
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12
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Allen PD, Ison JR. Sensitivity of the mouse to changes in azimuthal sound location: angular separation, spectral composition, and sound level. Behav Neurosci 2010; 124:265-77. [PMID: 20364886 DOI: 10.1037/a0018913] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Auditory spatial acuity was measured in mice using prepulse inhibition (PPI) of the acoustic startle reflex as the indicator response for stimulus detection. The prepulse was a "speaker swap" (SSwap), shifting a noise between two speakers located along the azimuth. Their angular separation, and the spectral composition and sound level of the noise were varied, as was the interstimulus interval (ISI) between SSwap and acoustic startle reflex elicitation. In Experiment 1 a 180 degrees SSwap of wide band noise (WBN) was compared with WBN Onset and Offset. SSwap and WBN Onset had near equal effects, but less than Offset. In Experiment 2 WBN SSwap was measured with speaker separations of 15, 22.5, 45, and 90 degrees . Asymptotic level and the growth rate of PPI increased with increased separation from 15 to 90 degrees , but even the 15 degrees SSwap provided significant PPI for the mean performance of the group. SSwap in Experiment 3 used octave band noise (2-4, 4-8, 8-16, or 16-32 kHz) and separations of 7.5 to 180 degrees . SSwap was most effective for the highest frequencies, with no significant PPI for SSwap below 8-16 kHz, or for separations of 7.5 degrees . In Experiment 4 SSwap had WBN sound levels from 40 to 78 dB SPL, and separations of 22.5, 45, 90, and 180 degrees : PPI increased with level, this effect varying with ISI and angular separation. These experiments extend the prior findings on sound localization in mice, and the dependence of PPI on ISI adds a reaction time-like dimension to this behavioral analysis.
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Affiliation(s)
- Paul D Allen
- Department of Neurobiology and Anatomy, University of Rochester Medical Center, Rochester, NY 14642, USA.
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Caspary DM, Ling L, Turner JG, Hughes LF. Inhibitory neurotransmission, plasticity and aging in the mammalian central auditory system. ACTA ACUST UNITED AC 2008; 211:1781-91. [PMID: 18490394 DOI: 10.1242/jeb.013581] [Citation(s) in RCA: 350] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Aging and acoustic trauma may result in partial peripheral deafferentation in the central auditory pathway of the mammalian brain. In accord with homeostatic plasticity, loss of sensory input results in a change in pre- and postsynaptic GABAergic and glycinergic inhibitory neurotransmission. As seen in development, age-related changes may be activity dependent. Age-related presynaptic changes in the cochlear nucleus include reduced glycine levels, while in the auditory midbrain and cortex, GABA synthesis and release are altered. Presumably, in response to age-related decreases in presynaptic release of inhibitory neurotransmitters, there are age-related postsynaptic subunit changes in the composition of the glycine (GlyR) and GABA(A) (GABA(A)R) receptors. Age-related changes in the subunit makeup of inhibitory pentameric receptor constructs result in altered pharmacological and physiological responses consistent with a net down-regulation of functional inhibition. Age-related functional changes associated with glycine neurotransmission in dorsal cochlear nucleus (DCN) include altered intensity and temporal coding by DCN projection neurons. Loss of synaptic inhibition in the superior olivary complex (SOC) and the inferior colliculus (IC) likely affect the ability of aged animals to localize sounds in their natural environment. Age-related postsynaptic GABA(A)R changes in IC and primary auditory cortex (A1) involve changes in the subunit makeup of GABA(A)Rs. In turn, these changes cause age-related changes in the pharmacology and response properties of neurons in IC and A1 circuits, which collectively may affect temporal processing and response reliability. Findings of age-related inhibitory changes within mammalian auditory circuits are similar to age and deafferentation plasticity changes observed in other sensory systems. Although few studies have examined sensory aging in the wild, these age-related changes would likely compromise an animal's ability to avoid predation or to be a successful predator in their natural environment.
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Affiliation(s)
- Donald M Caspary
- Southern Illinois University School of Medicine, Springfield, IL 62794, USA.
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14
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Sensorineural hearing loss and neural correlates of temporal acuity in the inferior colliculus of the C57BL/6 mouse. J Assoc Res Otolaryngol 2007; 9:90-101. [PMID: 17994264 DOI: 10.1007/s10162-007-0101-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Accepted: 09/25/2007] [Indexed: 10/22/2022] Open
Abstract
Perception of complex sounds depends on the encoding of the dynamic and static structures within the ongoing stimulus by the auditory system. Aging has been associated with deficits in both areas, thus, the difficulty that the elderly have in speech comprehension could due to hearing loss, or to a loss of temporal sensitivity, or some combination of both. We investigated the effects of sensorineural hearing loss (SNHL) on neural correlates of temporal resolution by recording the responses of inferior colliculus neurons to a gap detection paradigm. We used C57BL/6 (C57) strain of laboratory mouse, which carries the Ahl deafness gene that initiates a progressive high frequency SNHL beginning at about 2 months of age and rapidly progresses to total deafness by 18 months. We compared gap encoding from inferior collicular neurons from young, normal-hearing C57 mice and middle-aged, hearing-impaired, C57 mice, quantifying minimal gap threshold, and recovery functions. The proportion of unit types, spontaneous rates and degree of monotonicity were comparable between young and middle-aged C57 mice. As expected, single unit thresholds were elevated by 30-40 dB in middle-aged C57 mice. However, no significant differences in mean minimal gap thresholds or in the slopes of the gap recovery functions were found between the two age groups. Thus, the results suggest that moderate high frequency SNHL does not affect temporal processing as measured by the gap detection paradigm.
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Barsz K, Wilson WW, Walton JP. Reorganization of receptive fields following hearing loss in inferior colliculus neurons. Neuroscience 2007; 147:532-45. [PMID: 17540507 PMCID: PMC2614669 DOI: 10.1016/j.neuroscience.2007.04.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 04/02/2007] [Accepted: 04/16/2007] [Indexed: 11/28/2022]
Abstract
We explored frequency and intensity encoding in the inferior colliculus (IC) of the C57 mouse model of sensorineural hearing loss. Consistent with plasticity reported in the IC of other models of hearing loss, frequency response areas (FRAs) in hearing-impaired (HI) mice were broader with fewer high-frequency units than normal-hearing (NH) mice. The broad FRAs recorded from HI mice had lower cutoffs on the low frequency edge of the FRA. Characteristic frequency (CF) and sharpness of tuning (Q10) calculated from the FRA were used to divide the sample into four categories: low-CF sharp-FRA, low-CF broad-FRA, high-CF sharp-FRA, and high-CF broad-FRA units. Rate-intensity functions (RIFs) for CF tones and noise were used to determine the minimum and maximum response counts as well as the sound pressure levels resulting in 10%, 50%, and 90% of the maximum spike count. Tone RIFs of broad FRA units were shifted to the right of tone RIFs of sharp FRA units in both NH and HI mouse IC, regardless of the unit CF. The main effects of hearing loss were seen in the noise RIFs. The low-CF broad-FRA units in HI mice had elevated responses to noise, and the high-CF sharp-FRA units in HI mice had lower maximum rates, as compared with the units recorded from NH mice. These results suggest that, as the IC responds to peripheral hearing loss with changes in the representation of frequency, an altered balance between inhibitory and excitatory inputs to the neurons recorded from the HI mice alters aspects of the units' intensity encoding. This altered balance likely occurs, at least in part, outside of the IC.
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Affiliation(s)
- K Barsz
- Department of Otolaryngology and Neurobiology and Anatomy, University of Rochester Medical School, Rochester, NY 14642, USA
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Qin L, Chimoto S, Sakai M, Wang J, Sato Y. Comparison between offset and onset responses of primary auditory cortex ON-OFF neurons in awake cats. J Neurophysiol 2007; 97:3421-31. [PMID: 17360820 DOI: 10.1152/jn.00184.2007] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Primary auditory cortex (A1) neurons are believed not to carry much information about tonal offsets because A1 neurons in barbiturate-anesthetized animals are usually described as having only onset responses. We investigated tonal offset responses in comparison with onset responses in the caudal part of A1 of awake cats. Cells responding to both onsets and offsets were commonly found (59.2% of recorded cells). Offset responses usually co-occurred with phasic onset responses or phasic components of sustained responses. These ON-OFF cells had diverse combinations of offset- and onset-frequency-receptive field (FRF): offset-FRF was similar to onset-FRF, or narrower, wider, lower, or higher than onset-FRF. The distribution of FRF patterns was diffuse with no boundaries between the different FRF-pattern groups. The onset- versus offset-FRF pattern of each cell remained unchanged across multiple stimulus intensities. Mean offset response showed similar peak latency (19.5 vs. 21.5 ms), longer half-decay time (74.5 vs. 48.5 ms), and lower peak amplitude (20.4 vs. 35.9 spikes/s) compared with the mean onset response. Although offset responses were facilitated when preceded by the suppression of spike activity, they were still elicited without preceding spike suppression. It is concluded that neurons showing paired onset and offset responses are predominant in the caudal A1. Their frequency-filtering property is usually not static but dynamic, changing between sound onsets and offsets. Offset responses are similarly precise and salient as onset responses for effectively encoding sound offsets. They may be elicited as active spike responses to sound offset rather than simple rebound facilitation.
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Affiliation(s)
- Ling Qin
- Department of Physiology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi 409-3898, Japan
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Gleich O, Hamann I, Kittel MC, Klump GM, Strutz J. Forward masking in gerbils: The effect of age. Hear Res 2007; 223:122-8. [PMID: 17158007 DOI: 10.1016/j.heares.2006.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 11/02/2006] [Accepted: 11/02/2006] [Indexed: 10/23/2022]
Abstract
We investigated forward masking in 21 gerbils as a function of age (5-47 months) using 400ms maskers at 40dB SPL and a 20ms, 2.85kHz probe presented 2.5ms after the masker. Elevated thresholds for the unmasked probe were only observed in animals older than 3 years. Unmasked thresholds showed no significant age-dependent hearing loss in animals below 3 years of age. In these animals without peripheral hearing loss, we found a significant age-dependent increase of masker-induced threshold shift. A regression analysis revealed that threshold shift increased from 23dB in 1 year old gerbils to 37dB in 3 year old animals. Increased forward masking in these animals with no sign of peripheral hearing loss points to a central processing deficit.
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Affiliation(s)
- Otto Gleich
- ENT-Department, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany.
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Wang Y, Manis PB. Temporal coding by cochlear nucleus bushy cells in DBA/2J mice with early onset hearing loss. J Assoc Res Otolaryngol 2006; 7:412-24. [PMID: 17066341 PMCID: PMC1785302 DOI: 10.1007/s10162-006-0052-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Accepted: 07/27/2006] [Indexed: 11/30/2022] Open
Abstract
The bushy cells of the anterior ventral cochlear nucleus (AVCN) preserve or improve the temporal coding of sound information arriving from auditory nerve fibers (ANF). The critical cellular mechanisms entailed in this process include the specialized nerve terminals, the endbulbs of Held, and the membrane conductance configuration of the bushy cell. In one strain of mice (DBA/2J), an early-onset hearing loss can cause a reduction in neurotransmitter release probability, and a smaller and slower spontaneous miniature excitatory postsynaptic current (EPSC) at the endbulb synapse. In the present study, by using a brain slice preparation, we tested the hypothesis that these changes in synaptic transmission would degrade the transmission of timing information from the ANF to the AVCN bushy neuron. We show that the electrical excitability of bushy cells in hearing-impaired old DBA mice was different from that in young, normal-hearing DBA mice. We found an increase in the action potential (AP) firing threshold with current injection; a larger AP afterhyperpolarization; and an increase in the number of spikes produced by large depolarizing currents. We also tested the temporal precision of bushy cell responses to high-frequency stimulation of the ANF. The standard deviation of spikes (spike jitter) produced by ANF-evoked excitatory postsynaptic potentials (EPSPs) was largely unaffected in old DBA mice. However, spike entrainment during a 100-Hz volley of EPSPs was significantly reduced. This was not a limitation of the ability of bushy cells to fire APs at this stimulus frequency, because entrainment to trains of current pulses was unaffected. Moreover, the decrease in entrainment is not attributable to increased synaptic depression. Surprisingly, the spike latency was 0.46 ms shorter in old DBA mice, and was apparently attributable to a faster conduction velocity, since the evoked excitatory postsynaptic current (EPSC) latency was shorter in old DBA mice as well. We also tested the contribution of the low-voltage-activated K+ conductance (g (KLV)) on the spike latency by using dynamic clamp. Alteration in g (KLV) had little effect on the spike latency. To test whether these changes in DBA mice were simply a result of continued postnatal maturation, we repeated the experiments in CBA mice, a strain that shows normal hearing thresholds through this age range. CBA mice exhibited no reduction in entrainment or increased spike jitter with age. We conclude that the ability of AVCN bushy neurons to reliably follow ANF EPSPs is compromised in a frequency-dependent fashion in hearing-impaired mice. This effect can be best explained by an increase in spike threshold.
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Affiliation(s)
- Yong Wang
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina, 1115 Bioinformatics Building, CB#7070, Chapel Hill, NC 27599-7070, USA.
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Abstract
PURPOSE OF REVIEW Recent developments in age-related hearing loss (ARHL) are reviewed with an emphasis on their relation to the framework advocated by Schuknecht. More than a classification scheme, Schuknecht's typology incorporates testable hypotheses about the bases of ARHL. Since there is presently no widely accepted competing framework, research in this area should be aimed at supporting, modifying, or replacing Schuknecht scheme. Only recently has our understanding of cellular changes and gene/environment interactions in ARHL achieved the level needed for hypothesis-driven experiments in this area. RECENT FINDINGS New findings largely support or amplify aspects of Schuknecht's framework. Consideration of the kinds of cells involved in ARHL has broadened to include more nonsensory and supporting cells. This should provide more complete criteria for comparing models, and for diagnosing particular forms of ARHL. Newly discovered genetic effects and more detailed comparisons have imparted mechanistic significance to the often-noted similarity between sensory ARHL and noise injury. Recent comparative studies, and studies of cell replacement in the cochlear lateral wall, suggest variations in the relation between strial and ligament pathology, and indicate why cell loss occurs during aging. Mouse models carrying mutations affecting processes that may give rise to ARHL are receiving increased attention, even as detailed studies bolster support for mice as valid ARHL models. SUMMARY Using Schuknecht's framework as a guide, basic research can now seek to model specific forms of ARHL by combining genetic defects and appropriate environmental conditions. Identification of distinct risk factors for age-related degeneration of organ of Corti, afferent neurons, and stria would verify a key tenet of Schuknecht's scheme, and point the way to interventions.
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Affiliation(s)
- Kevin K Ohlemiller
- Department of Otolaryngology, Washington University, St. Louis, Missouri, USA
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