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Hong SA, Kuziez D, Das N, Harris D, Brunworth JD. Hazardous sound outputs of white noise devices intended for infants. Int J Pediatr Otorhinolaryngol 2021; 146:110757. [PMID: 33992973 DOI: 10.1016/j.ijporl.2021.110757] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/27/2021] [Accepted: 05/06/2021] [Indexed: 11/19/2022]
Abstract
OBJECTIVES To measure the sound intensity of popular infant white noise machines and Apple iPhone applications (apps) as they vary with volume setting and distance, and compare these output levels with current National Institute for Occupational Safety and Health (NIOSH) noise exposure threshold recommendations. METHODS A total of eight infant white noise machines and six iPhone applications were included in the study based on product rating, number of ratings, and cost. The NIOSH Sound Level Meter application through the Apple App Store was used to measure output levels in A-weighted decibels (dBA). Each device was tested at its lowest and highest volume setting and at speaker-to-microphone distances simulating placement within a crib (10 cm), just outside of a crib rail (30 cm), and on a nightstand across the room (100 cm). RESULTS At the minimum volume setting, no device exceeded the NIOSH recommended noise exposure threshold of 85 dBA at any distance tested. At maximum volume setting, nine out of fourteen (64.3%) devices exceeded output levels of 85 dBA at a speaker-to-microphone distance of 10 cm. No device exceeded the recommended threshold at its maximal volume when placed 30 cm or 100 cm away. CONCLUSION Excessive white noise exposure has the potential to lead to noise-induced hearing loss and other adverse health effects in the neonatal and infant population. We recommend conservative use of white noise machines and apps by avoiding maximal volume setting and placing any device well outside of the crib or at least 30 cm away from the child. To promote safe use of white noise devices, future studies are needed to fully understand the association between early noise exposure and hearing loss in infants.
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Affiliation(s)
- Scott A Hong
- Department of Otolaryngology - Head and Neck Surgery, St. Louis University Hospital, 1008 S Spring Ave, St. Louis, Missouri, 63104, USA.
| | - Duaa Kuziez
- Saint Louis University School of Medicine, 1402 S Grand Blvd, St. Louis, Missouri, 63104, USA.
| | - Nikhil Das
- Saint Louis University School of Medicine, 1402 S Grand Blvd, St. Louis, Missouri, 63104, USA.
| | - Dave Harris
- Department of Audiology, St. Louis University Hospital, 1225 S Grand Blvd, St. Louis, Missouri, 63104, USA.
| | - Joseph D Brunworth
- Department of Otolaryngology - Head and Neck Surgery, St. Louis University Hospital, 1008 S Spring Ave, St. Louis, Missouri, 63104, USA.
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Homma NY, Hullett PW, Atencio CA, Schreiner CE. Auditory Cortical Plasticity Dependent on Environmental Noise Statistics. Cell Rep 2021; 30:4445-4458.e5. [PMID: 32234479 PMCID: PMC7326484 DOI: 10.1016/j.celrep.2020.03.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 08/07/2019] [Accepted: 03/05/2020] [Indexed: 01/14/2023] Open
Abstract
During critical periods, neural circuits develop to form receptive fields that adapt to the sensory environment and enable optimal performance of relevant tasks. We hypothesized that early exposure to background noise can improve signal-in-noise processing, and the resulting receptive field plasticity in the primary auditory cortex can reveal functional principles guiding that important task. We raised rat pups in different spectro-temporal noise statistics during their auditory critical period. As adults, they showed enhanced behavioral performance in detecting vocalizations in noise. Concomitantly, encoding of vocalizations in noise in the primary auditory cortex improves with noise-rearing. Significantly, spectro-temporal modulation plasticity shifts cortical preferences away from the exposed noise statistics, thus reducing noise interference with the foreground sound representation. Auditory cortical plasticity shapes receptive field preferences to optimally extract foreground information in noisy environments during noise-rearing. Early noise exposure induces cortical circuits to implement efficient coding in the joint spectral and temporal modulation domain. After rearing rats in moderately loud spectro-temporally modulated background noise, Homma et al. investigated signal-in-noise processing in the primary auditory cortex. Noise-rearing improved vocalization-in-noise performance in both behavioral testing and neural decoding. Cortical plasticity shifted neuronal spectro-temporal modulation preferences away from the exposed noise statistics.
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Affiliation(s)
- Natsumi Y Homma
- Coleman Memorial Laboratory, Department of Otolaryngology - Head and Neck Surgery, University of California, San Francisco, San Francisco, CA 94143, USA; Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Patrick W Hullett
- Coleman Memorial Laboratory, Department of Otolaryngology - Head and Neck Surgery, University of California, San Francisco, San Francisco, CA 94143, USA; Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Craig A Atencio
- Coleman Memorial Laboratory, Department of Otolaryngology - Head and Neck Surgery, University of California, San Francisco, San Francisco, CA 94143, USA; Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Christoph E Schreiner
- Coleman Memorial Laboratory, Department of Otolaryngology - Head and Neck Surgery, University of California, San Francisco, San Francisco, CA 94143, USA; Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, CA 94143, USA.
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Reinhard SM, Abundez-Toledo M, Espinoza K, Razak KA. Effects of developmental noise exposure on inhibitory cell densities and perineuronal nets in A1 and AAF of mice. Hear Res 2019; 381:107781. [DOI: 10.1016/j.heares.2019.107781] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 07/26/2019] [Accepted: 08/06/2019] [Indexed: 10/26/2022]
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Xia C, Yin M, Pan P, Fang F, Zhou Y, Ji Y. Long-term exposure to moderate noise induces neural plasticity in the infant rat primary auditory cortex. Anim Cells Syst (Seoul) 2019; 23:260-269. [PMID: 31489247 PMCID: PMC6711034 DOI: 10.1080/19768354.2019.1643782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 06/27/2019] [Accepted: 06/27/2019] [Indexed: 11/17/2022] Open
Abstract
Previous studies have reported that rearing infant rat pups in continuous moderate-level noise delayed the formation of topographic representational order and the refinement of response selectivity in the primary auditory (A1) cortex. The present study further verified that exposure to long-term moderate-intensity white noise (70 dB sound pressure level) from postnatal day (P) 12 to P30 elevated the hearing thresholds of infant rats. Compared with age-matched control rats, noise exposure (NE) rats had elevated hearing thresholds ranging from low to high frequencies, accompanied by decreased amplitudes and increased latencies of the two initial auditory brainstem response waves. The power of raw local field potential oscillations and high-frequency β oscillation in the A1 cortex of NE rats were larger, whereas the power of high-frequency γ oscillation was smaller than that of control rats. In addition, the expression levels of five glutamate receptor (GluR) subunits in the A1 cortex of NE rats were decreased with laminar specificity. These results suggest that the altered neural excitability and decreased GluR expression may underlie the delay of functional maturation in the A1 cortex, and may have implications for the treatment of hearing impairment induced by environmental noise.
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Affiliation(s)
- Chenchen Xia
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai, People's Republic of China
| | - Manli Yin
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai, People's Republic of China
| | - Ping Pan
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai, People's Republic of China
| | - Fanghao Fang
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai, People's Republic of China
| | - You Zhou
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai, People's Republic of China.,Department of Otolaryngology-Head and Neck Surgery, Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China.,Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, People's Republic of China
| | - Yonghua Ji
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai, People's Republic of China
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Wang F, Liu J, Zhang J. Early postnatal noise exposure degrades the stimulus-specific adaptation of neurons in the rat auditory cortex in adulthood. Neuroscience 2019; 404:1-13. [DOI: 10.1016/j.neuroscience.2019.01.064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/09/2019] [Accepted: 01/30/2019] [Indexed: 12/11/2022]
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The effect of noise exposure during the developmental period on the function of the auditory system. Hear Res 2017; 352:1-11. [DOI: 10.1016/j.heares.2016.03.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 03/14/2016] [Indexed: 12/12/2022]
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Brief Stimulus Exposure Fully Remediates Temporal Processing Deficits Induced by Early Hearing Loss. J Neurosci 2017; 37:7759-7771. [PMID: 28706081 DOI: 10.1523/jneurosci.0916-17.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 06/24/2017] [Accepted: 07/08/2017] [Indexed: 12/30/2022] Open
Abstract
In childhood, partial hearing loss can produce prolonged deficits in speech perception and temporal processing. However, early therapeutic interventions targeting temporal processing may improve later speech-related outcomes. Gap detection is a measure of auditory temporal resolution that relies on the auditory cortex (ACx), and early auditory deprivation alters intrinsic and synaptic properties in the ACx. Thus, early deprivation should induce deficits in gap detection, which should be reflected in ACx gap sensitivity. We tested whether earplugging-induced, early transient auditory deprivation in male and female Mongolian gerbils caused correlated deficits in behavioral and cortical gap detection, and whether these could be rescued by a novel therapeutic approach: brief exposure to gaps in background noise. Two weeks after earplug removal, animals that had been earplugged from hearing onset throughout auditory critical periods displayed impaired behavioral gap detection thresholds (GDTs), but this deficit was fully reversed by three 1 h sessions of exposure to gaps in noise. In parallel, after earplugging, cortical GDTs increased because fewer cells were sensitive to short gaps, and gap exposure normalized this pattern. Furthermore, in deprived animals, both first-spike latency and first-spike latency jitter increased, while spontaneous and evoked firing rates decreased, suggesting that deprivation causes a wider range of perceptual problems than measured here. These cortical changes all returned to control levels after gap exposure. Thus, brief stimulus exposure, perhaps in a salient context such as the unfamiliar placement into a testing apparatus, rescued impaired gap detection and may have potential as a remediation tool for general auditory processing deficits.SIGNIFICANCE STATEMENT Hearing loss in early childhood leads to impairments in auditory perception and language processing that can last well beyond the restoration of hearing sensitivity. Perceptual deficits can be improved by training, or by acoustic enrichment in animal models, but both approaches involve extended time and effort. Here, we used a novel remediation technique, brief periods of auditory stimulus exposure, to fully remediate cortical and perceptual deficits in gap detection induced by early transient hearing loss. This technique also improved multiple cortical response properties. Rescue by this efficient exposure regime may have potential as a therapeutic tool to remediate general auditory processing deficits in children with perceptual challenges arising from early hearing loss.
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Alkharabsheh A, Xiong F, Xiong B, Manohar S, Chen G, Salvi R, Sun W. Early age noise exposure increases loudness perception - A novel animal model of hyperacusis. Hear Res 2017; 347:11-17. [DOI: 10.1016/j.heares.2016.06.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 06/04/2016] [Accepted: 06/15/2016] [Indexed: 11/26/2022]
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Salehi MS, Namavar MR, Tamadon A, Bahmani R, Jafarzadeh Shirazi MR, Khazali H, Dargahi L, Pandamooz S, Mohammad-Rezazadeh F, Rashidi FS. The Effects of Acoustic White Noise on the Rat Central Auditory System During the Fetal and Critical Neonatal Periods: A Stereological Study. Noise Health 2017; 19:24-30. [PMID: 28164936 PMCID: PMC5397999 DOI: 10.4103/1463-1741.199239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
AIM To evaluate the effects of long-term, moderate level noise exposure during crucial periods of rat infants on stereological parameters of medial geniculate body (MGB) and auditory cortex. MATERIALS AND METHODS Twenty-four male offspring of 12 pregnant rats were divided into four groups: fetal-to-critical period group, which were exposed to noise from the last 10 days of fetal life till postnatal day (PND) 29; fetal period group that exposed to noise during the last 10 days of fetal life; critical period group, exposed to noise from PND 15 till PND 29, and control group. White noise at 90 dB for 2 h per day was used. STATISTICAL ANALYSIS USED Variance for variables was performed using Proc GLM followed by mean comparison by Duncan's multiple range test. RESULTS Numerical density of neurons in MGB of fetal-to-critical period group was lower than control group. Similar results were seen in numerical density of neurons in layers IV and VI of auditory cortex. Furthermore, no significant difference was observed in the volume of auditory cortex among groups, and only MGB volume in fetal-to-critical period group was higher than other groups. Estimated total number of neurons in MGB was not significantly different among groups. CONCLUSION It seems necessary to prevent long-term moderate level noise exposure during fetal-to-critical neonatal period.
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Affiliation(s)
- Mohammad Saied Salehi
- Department of Physiology, Faculty of Biological Sciences and Technology, Shahid Beheshti University, Tehran, Iran
- Department of Animal Sciences, College of Agriculture, Shiraz University, Shiraz, Iran
| | - Mohammad Reza Namavar
- Histomorphometry and Stereology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Clinical Neurology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Amin Tamadon
- Transgenic Technology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Raziyeh Bahmani
- Department of Audiology, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Homayoun Khazali
- Department of Physiology, Faculty of Biological Sciences and Technology, Shahid Beheshti University, Tehran, Iran
| | - Leila Dargahi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Sareh Pandamooz
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Fatemeh Sadat Rashidi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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10
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Jiang C, Xu X, Yu L, Xu J, Zhang J. Environmental enrichment rescues the degraded auditory temporal resolution of cortical neurons induced by early noise exposure. Eur J Neurosci 2015; 42:2144-54. [DOI: 10.1111/ejn.12975] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Revised: 06/02/2015] [Accepted: 06/02/2015] [Indexed: 12/26/2022]
Affiliation(s)
- Cuiping Jiang
- Key Laboratory of Brain Functional Genomics; Ministry of Education; Shanghai Key Laboratory of Brain Functional Genomics; NYU-ECNU Institute of Brain and Cognitive Science at NYU Shanghai; School of Life Sciences; East China Normal University; Shanghai 200062 China
| | - Xiaoxiao Xu
- Key Laboratory of Brain Functional Genomics; Ministry of Education; Shanghai Key Laboratory of Brain Functional Genomics; NYU-ECNU Institute of Brain and Cognitive Science at NYU Shanghai; School of Life Sciences; East China Normal University; Shanghai 200062 China
| | - Liping Yu
- Key Laboratory of Brain Functional Genomics; Ministry of Education; Shanghai Key Laboratory of Brain Functional Genomics; NYU-ECNU Institute of Brain and Cognitive Science at NYU Shanghai; School of Life Sciences; East China Normal University; Shanghai 200062 China
| | - Jinghong Xu
- Key Laboratory of Brain Functional Genomics; Ministry of Education; Shanghai Key Laboratory of Brain Functional Genomics; NYU-ECNU Institute of Brain and Cognitive Science at NYU Shanghai; School of Life Sciences; East China Normal University; Shanghai 200062 China
| | - Jiping Zhang
- Key Laboratory of Brain Functional Genomics; Ministry of Education; Shanghai Key Laboratory of Brain Functional Genomics; NYU-ECNU Institute of Brain and Cognitive Science at NYU Shanghai; School of Life Sciences; East China Normal University; Shanghai 200062 China
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11
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Hugh SC, Wolter NE, Propst EJ, Gordon KA, Cushing SL, Papsin BC. Infant sleep machines and hazardous sound pressure levels. Pediatrics 2014; 133:677-81. [PMID: 24590753 DOI: 10.1542/peds.2013-3617] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND AND OBJECTIVE Infant "sleep machines" (ISMs) produce ambient noise or noise to mask other sounds in an infant's room with the goal of increasing uninterrupted sleep. We suggest that the consistent use of these devices raises concerns for increasing an infant's risk of noise-induced hearing loss. We therefore sought to determine the maximum output levels of these sleep machines. METHODS Sound levels of 14 ISMs played at maximum volume were measured at 30, 100, and 200 cm from the machine using correction factors to account for a 6-month-old's ear canal. RESULTS Maximum sound levels at 30 cm were >50 A-weighted dB for all devices, which is the current recommended noise limit for infants in hospital nurseries. Three machines produced output levels >85 A-weighted dB, which, if played at these levels for >8 hours, exceeds current occupational limits for accumulated noise exposure in adults and risks noise-induced hearing loss. CONCLUSIONS ISMs are capable of producing output sound pressure levels that may be damaging to infant hearing and auditory development. We outline recommendations for safer operation of these machines.
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Affiliation(s)
- Sarah C Hugh
- Department of Otolaryngology, Head and Neck Surgery, University of Toronto, Toronto, Canada; and
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12
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The Effect of Weak Background Noise on The Frequency Tuning of Neurons in The Rat Auditory Cortex*. PROG BIOCHEM BIOPHYS 2012. [DOI: 10.3724/sp.j.1206.2012.00114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Uran S, Aon-Bertolino M, Caceres L, Capani F, Guelman L. Rat hippocampal alterations could underlie behavioral abnormalities induced by exposure to moderate noise levels. Brain Res 2012; 1471:1-12. [DOI: 10.1016/j.brainres.2012.06.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 06/15/2012] [Accepted: 06/15/2012] [Indexed: 12/21/2022]
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Changes in the distribution of calbindin D28-k, parvalbumin, and calretinin in the hippocampus of the circling mouse. Brain Res 2012; 1437:58-68. [DOI: 10.1016/j.brainres.2011.12.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 11/18/2011] [Accepted: 12/04/2011] [Indexed: 01/29/2023]
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Sanes DH, Woolley SMN. A behavioral framework to guide research on central auditory development and plasticity. Neuron 2011; 72:912-29. [PMID: 22196328 PMCID: PMC3244881 DOI: 10.1016/j.neuron.2011.12.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2011] [Indexed: 01/14/2023]
Abstract
The auditory CNS is influenced profoundly by sounds heard during development. Auditory deprivation and augmented sound exposure can each perturb the maturation of neural computations as well as their underlying synaptic properties. However, we have learned little about the emergence of perceptual skills in these same model systems, and especially how perception is influenced by early acoustic experience. Here, we argue that developmental studies must take greater advantage of behavioral benchmarks. We discuss quantitative measures of perceptual development and suggest how they can play a much larger role in guiding experimental design. Most importantly, including behavioral measures will allow us to establish empirical connections among environment, neural development, and perception.
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Affiliation(s)
- Dan H Sanes
- Center for Neural Science, 4 Washington Place, New York University, New York, NY 10003, USA.
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16
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Moderate noise induced cognition impairment of mice and its underlying mechanisms. Physiol Behav 2011; 104:981-8. [DOI: 10.1016/j.physbeh.2011.06.018] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 06/18/2011] [Accepted: 06/20/2011] [Indexed: 11/22/2022]
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Abstract
Sensory experience during development can modify the CNS and alter adult perceptual skills. While this principle draws support from deprivation or chronic stimulus exposure studies, the effect of training is addressed only in adults. Here, we asked whether a brief period of training during development can exert a unique impact on adult perceptual skills. Juvenile gerbils were trained to detect amplitude modulation (AM), a stimulus feature elemental to animal communication sounds. When the performance of these juvenile-trained animals was subsequently assessed in adulthood, it was superior to a control group that received an identical regimen of training as adults. The juvenile-trained animals displayed significantly better AM detection thresholds. This was not observed in an adult group that received only exposure to AM stimuli as juveniles. To determine whether enhanced adult performance was due solely to learning the conditioned avoidance procedure, juveniles were trained on frequency modulation (FM) detection, and subsequently assessed on AM detection as adults. These animals displayed significantly poorer AM detection thresholds than all other groups. Thus, training on a specific auditory task (AM detection) during development provided a benefit to performance on that task in adulthood, whereas an identical training regimen in adulthood did not bring about this enhancement. In contrast, there was a cost, in adulthood, following developmental training on a different task (FM detection). Together, the results demonstrate a period of heightened sensitivity in the developing CNS such that behavioral training in juveniles has a unique impact on adult behavioral capabilities.
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Yu YF, Zhai F, Dai CF, Hu JJ. The relationship between age-related hearing loss and synaptic changes in the hippocampus of C57BL/6J mice. Exp Gerontol 2011; 46:716-22. [PMID: 21586320 DOI: 10.1016/j.exger.2011.04.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 04/20/2011] [Accepted: 04/28/2011] [Indexed: 10/18/2022]
Abstract
To explore the relationship between age-related hearing loss (presbycusis) and synaptic degeneration in the hippocampal CA3 region of C57BL/6J mice, we investigated both cognitive performance and synaptic changes within the hippocampus of C57BL/6J mice from three age groups of 6-8, 24-26, and 42-44 weeks; CBA/CaJ mice served as controls. The auditory brainstem response was used as a measure of hearing threshold, and cognitive behavior was evaluated using the Morris water maze. The ultrastructure of synapses was observed with transmission electron microscopy, and the quantity and distribution of the synaptic markers synaptophysin and PSD-95 were observed with immunohistochemistry. The hearing threshold of C57BL/6J mice was significantly higher at 24-26 weeks than at 6-8 weeks, and hearing loss was profound at 42-44 weeks. This was accompanied by progressive degeneration of synapses within the auditory cortex. In contrast, the hearing threshold of CBA/CaJ mice was relatively unchanged at 24-26 weeks of age, and these mice developed only mild hearing loss at 42-44 weeks of age. Interestingly, C57BL/6J, but not CBA/CaJ mice clearly exhibited both decreased performance in the Morris water maze and degeneration of synapses within the hippocampus. We therefore conclude that age-related hearing loss is accompanied by the degeneration of synapses in the hippocampal CA3 region of C57BL/6J mice.
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Affiliation(s)
- Ya-Feng Yu
- Department of Otology & Skull Base Surgery, Eye Ear Nose & Throat Hospital, Fudan University, Shanghai 200031, China
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Sun W, Tang L, Allman BL. Environmental noise affects auditory temporal processing development and NMDA-2B receptor expression in auditory cortex. Behav Brain Res 2010; 218:15-20. [PMID: 21094188 DOI: 10.1016/j.bbr.2010.11.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 11/06/2010] [Accepted: 11/11/2010] [Indexed: 10/18/2022]
Abstract
Auditory temporal processing is essential for sound discrimination and speech comprehension. Under normal developmental conditions, temporal processing acuity improves with age. As recent animal studies have shown that the functional development of the auditory cortex (AC) is impaired by early life exposure to environmental noise (i.e., continuous, moderate-level, white noise), here we investigated whether the normal age-related improvement in temporal processing acuity is sensitive to delayed development of the AC. We used a behavioral paradigm, the gap-induced prepulse inhibition of the acoustic startle reflex, to assess the gap detection threshold, and provide a comparison of temporal processing acuity between environmental noise-reared rats and age-matched controls. Moreover, because age-related changes normally occur in the relative expression of different N-methyl-D-aspartate (NMDA) receptor subunits, we assessed the level of protein expression of NMDA-2A and 2B receptors (NR2A and NR2B respectively) in the AC after environmental noise-rearing. As hypothesized, rats reared in environmental noise showed (1) poor temporal processing acuity as adults (i.e., gap detection threshold remained elevated at a juvenile-like level), and (2) an increased level of NR2B protein expression compared to age-matched controls. This poor temporal processing acuity represented delayed development rather than permanent impairment, as moving these environmental noise-reared rats to normal acoustic conditions improved their gap detection threshold to an age-appropriate level. Furthermore, housing normally reared, adult rats in environmental noise for two months did not affect their already-mature gap detection threshold. Thus, masking normal sound inputs with environmental noise during early life, but not adulthood, impairs temporal processing acuity as assessed with the gap detection threshold.
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Affiliation(s)
- Wei Sun
- Center for Hearing and Deafness, The State University of New York at Buffalo, 3435 Main Street, Buffalo, NY 14214, USA.
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Bureš Z, Grécová J, Popelář J, Syka J. Noise exposure during early development impairs the processing of sound intensity in adult rats. Eur J Neurosci 2010; 32:155-64. [DOI: 10.1111/j.1460-9568.2010.07280.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Grécová J, Bureš Z, Popelář J, Šuta D, Syka J. Brief exposure of juvenile rats to noise impairs the development of the response properties of inferior colliculus neurons. Eur J Neurosci 2009; 29:1921-30. [DOI: 10.1111/j.1460-9568.2009.06739.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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The effect of postnatal exposure to noise on sound level processing by auditory cortex neurons of rats in adulthood. Physiol Behav 2009; 97:369-73. [PMID: 19296909 DOI: 10.1016/j.physbeh.2009.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Revised: 03/07/2009] [Accepted: 03/09/2009] [Indexed: 10/21/2022]
Abstract
Most people are exposed daily to some level and duration of environmental noise. The aim of the present study was to determine the effect of postnatal exposure to a moderate level of noise on sound level processing by neurons in the primary auditory cortex of rats in adulthood. The cortical neuron response to sound stimuli was investigated in three groups of rats. Two groups, either in the critical period of postnatal hearing development or in adulthood, were exposed to 80 dB SPL interrupted white noise for 8 h/day for 2 weeks. The control group consisted of adult rats that were not exposed to the white noise. Seven weeks later, the minimum threshold, the first spike latency, the dynamic range and the slope of the rate-level functions of cortical neuron response to a sound stimulus were determined. The cortical neurons in young rats exposed to the noise had a significantly higher minimum threshold, a longer first spike latency, a shorter dynamic range and a bigger slope in rate-level functions compared with the control group. The group in which adult rats were exposed to the white noise, however, did not have a significant change of sound level processing by the auditory cortical neurons. These results demonstrated that young rats were more susceptible to noise exposure affecting the cortical neuron processing of sound levels.
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