目的探讨耳蜗电图对噪声导致的隐性听力损失的早期诊断价值。方法选取36例18～40岁的常频听阈正常受试者,其中18例有噪声暴露史的工人作为噪声暴露组,18例无噪声暴露史的正常受试者作为对照组,分别行纯音听阈测试(常频+高频)、噪声下言...目的探讨耳蜗电图对噪声导致的隐性听力损失的早期诊断价值。方法选取36例18～40岁的常频听阈正常受试者,其中18例有噪声暴露史的工人作为噪声暴露组,18例无噪声暴露史的正常受试者作为对照组,分别行纯音听阈测试(常频+高频)、噪声下言语测试以及耳蜗电图测试,比较各组检查结果。结果噪声暴露组和对照组18、20 kHz听阈检出率分别为55.6%、33.3%和88.9%、88.3%,噪声暴露组低于对照组,差异有统计学意义(P<0.05);10、12.5 kHz平均听阈分别为11.94±15.16、16.39±20.87 dB HL和3.89±15.20、6.94±20.87 dB HL,噪声暴露组高于对照组(P<0.05);言语测试结果示噪声暴露组和对照组信噪比损失平均值分别为4.62±2.52 dB和1.44±2.90 dB,噪声暴露组高于对照组(P<0.01)。耳蜗电图测试结果示,噪声暴露组SP/AP振幅比在96和90 dB nHL刺激强度下高于对照组,差异有统计学意义(P<0.05),SP/AP面积比在96 dB nHL刺激强度下高于对照组,差异有统计学意义(P<0.05)。结论高强度刺激下(96 dB nHL)耳蜗电图SP/AP振幅比和面积比对噪声导致的隐性听力损失检测有一定的参考价值。展开更多
Duration is a salient feature of acoustic signals including speech. Duration tuning was first reported in frogs and later in echolocating bats. More recently, duration tuning has been reported in non-echolocating mamm...Duration is a salient feature of acoustic signals including speech. Duration tuning was first reported in frogs and later in echolocating bats. More recently, duration tuning has been reported in non-echolocating mammals and appears to be a fundamental encoding mechanism throughout the animal kingdom. However, the duration tuning reported in these non-echolocating mammals appears to be much weaker than that in the previous studies on bats. In contrast to this finding, our recent study reported that duration tuning in the IC in guinea pigs appeared to be strong when it was measured using an appropriate temporal window. With such a temporal window, duration tuning was found to be compatible with that of echo-locating bats. In the present report, we further demonstrate that duration tuning in the IC of this species is established by interaction between excitation and GABAergic inhibition. In addition to overall increase in responsiveness, application of bicuculline(BIC), a GABA-A receptor antagonist, was found to significantly reduce or eliminate duration selectivity in 44 out of the 67 neurons that showed clear duration tuning from a sample of 340 neurons.展开更多
Neuronal ion channels of different types often do not function independently but will inhibit or potentiate the activity of other types of channels,a process called cross-talk.The N-methyl-D-aspartate receptor (NMDA r...Neuronal ion channels of different types often do not function independently but will inhibit or potentiate the activity of other types of channels,a process called cross-talk.The N-methyl-D-aspartate receptor (NMDA receptor) and the γ-aminobutyric acid type A receptor (GABAA receptor) are important excitatory and inhibitory receptors in the central nervous system,respectively.Currently,cross-talk between the NMDA receptor and the GABAA receptor,particularly in the central auditory system,is not well understood.In the present study,we investigated functional interactions between the NMDA receptor and the GABAA receptor using whole-cell patch-clamp techniques in cultured neurons from the inferior colliculus,which is an important nucleus in the central auditory system.We found that the currents induced by aspartate at 100 μmol L-1 were suppressed by the pre-perfusion of GABA at 100 μmol L-1,indicating cross-inhibition of NMDA receptors by activation of GABAA receptors.Moreover,we found that the currents induced by GABA at 100 μmol L-1 (IGABA) were not suppressed by the pre-perfusion of 100 μmol L-1 aspartate,but those induced by GABA at 3 μmol L-1 were suppressed,indicating concentration-dependent cross-inhibition of GABAA receptors by activation of NMDA receptors.In addition,inhibition of IGABA by aspartate was not affected by blockade of voltage-dependent Ca2+ channels with CdCl2 in a solution that contained Ca2+,however,CdCl2 effectively attenuated the inhibition of IGABA by aspartate when it was perfused in a solution that contained Ba2+ instead of Ca2+ or a solution that contained Ca2+ and 10 mmol L-1 BAPTA,a membrane-permeable Ca2+ chelator,suggesting that this inhibition is mediated by Ca2+ influx through NMDA receptors,rather than voltage-dependent Ca2+ channels.Finally,KN-62,a potent inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMKII),reduced the inhibition of IGABA by aspartate,indicating the involvement of CaMKII in this cross-inhibition.Our study demonstrates a functional interaction between NMDA and GABAA receptors in the inferior colliculus of rats.The presence of cross-talk between these receptors suggests that the mechanisms underlying information processing in the central auditory system may be more complex than previously believed.展开更多
Background:Complex noise and its relation to hearing loss are difficult to measure and evaluate.In complex noise measurement,individual exposure results may not accurately represent lifetime noise exposure.Thus,the me...Background:Complex noise and its relation to hearing loss are difficult to measure and evaluate.In complex noise measurement,individual exposure results may not accurately represent lifetime noise exposure.Thus,the mean LAeq,8 h values of individuals in the same workgroup were also used to represent LAeq,8h in our study.Our study aimed to explore whether the mean exposure levels of workers in the same workgroup represented real noise exposure better than individual exposure levels did.Methods:A cross-sectional study was conducted to establish a model for cumulative noise exposure (CNE) and hearing loss in 205 occupational noise-exposed workers who were recruited from two large automobile manufacturers in China.We used a personal noise dosimeter and a questionnaire to determine the workers' occupational noise exposure levels and exposure times,respectively.A qualified audiologist used standardized audiometric procedures to assess hearing acuity after at least 16 h of noise avoidance.Results:We observed that 88.3％ of workers were exposed to more than 85 dB(A) of occupational noise (mean:89.3 ± 4.2 dB(A)).The personal CNE (CNEp) and workgroup CNE (CNEg) were 100.5 ± 4.7 dB(A) and 100.5 ± 2.9 dB(A),respectively.In the binary logistic regression analysis,we established a regression model with high-frequency hearing loss as the dependent variable and CNE as the independent variable.The Wald value was 5.014 with CNEp as the independent variable and 8.653 with CNEg as the independent variable.Furthermore,we found that the figure for CNEg was more similar to the stationary noise reference than CNEp was.The CNEg model was better than the CNEp model.In this circumstance,we can measure some subjects instead of the whole workgroup and save manpower.Conclusions:In a complex noise environment,the measurements of average noise exposure level of the workgroup can improve the accuracy and save manpower.展开更多
Rebound depolarization （RD） is a response to the offset from hyperpolarization of the neuronal mem- brane potential and is an important mechanism for the synaptic processing of inhibitory signals. In the present stu...Rebound depolarization （RD） is a response to the offset from hyperpolarization of the neuronal mem- brane potential and is an important mechanism for the synaptic processing of inhibitory signals. In the present study, we characterized RD in neurons of the rat medial geniculate body （MGB）, a nucleus of the auditory thala- mus, using whole-cell patch-clamp and brain slices. RD was proportional in strength to the duration and magnitude of the hyperpolarization; was effectively blocked by Ni2＋ or Mibefradil; and was depressed when the resting membrane potential was hyperpolarized by blocking hyperpolarization-activated cyclic nucleotide-gated （HCN） channels with ZD7288 or by activating G-protein-gated inwardly-rectifying K＋ （GIRK） channels with baclofen. Our results demonstrated that RD in MGB neurons, which is carried by T-type Ca2＋ channels, is critically regulated by HCN channels and likely by GIRK channels.展开更多
Summary What is already known about this topic?Occupational noise-induced hearing loss(NIHL)has been the second most common occupational disease in China.Noise energy is the main risk factor for occupational NIHL.Evid...Summary What is already known about this topic?Occupational noise-induced hearing loss(NIHL)has been the second most common occupational disease in China.Noise energy is the main risk factor for occupational NIHL.Evidence shows the temporal structure of noise(as indicated by kurtosis metric)contribute to the development of NIHL.However,the role of the kurtosis metric in evaluating the risk of occupational NIHL associated with complex noise has been rarely reported.展开更多
It is well known that high-level noise exposure can lead to hearing loss.Noise-induced hearing loss(NIHL)continues to be one of the major occupational health hazards.An underlying assumption in current noise standards...It is well known that high-level noise exposure can lead to hearing loss.Noise-induced hearing loss(NIHL)continues to be one of the major occupational health hazards.An underlying assumption in current noise standards,e.g.,ISO 1999:2013(1),is that hearing loss is related to the total energy of the exposure.Thus,the risk of NIHL can be predicted according to the ISO 1999 prediction model.Unfortunately,the validity of the prediction model to correctly predict the NIHL for all types of noise exposure is still under question,especially for complex noise of impulsive character.展开更多
文摘目的探讨耳蜗电图对噪声导致的隐性听力损失的早期诊断价值。方法选取36例18～40岁的常频听阈正常受试者,其中18例有噪声暴露史的工人作为噪声暴露组,18例无噪声暴露史的正常受试者作为对照组,分别行纯音听阈测试(常频+高频)、噪声下言语测试以及耳蜗电图测试,比较各组检查结果。结果噪声暴露组和对照组18、20 kHz听阈检出率分别为55.6%、33.3%和88.9%、88.3%,噪声暴露组低于对照组,差异有统计学意义(P<0.05);10、12.5 kHz平均听阈分别为11.94±15.16、16.39±20.87 dB HL和3.89±15.20、6.94±20.87 dB HL,噪声暴露组高于对照组(P<0.05);言语测试结果示噪声暴露组和对照组信噪比损失平均值分别为4.62±2.52 dB和1.44±2.90 dB,噪声暴露组高于对照组(P<0.01)。耳蜗电图测试结果示,噪声暴露组SP/AP振幅比在96和90 dB nHL刺激强度下高于对照组,差异有统计学意义(P<0.05),SP/AP面积比在96 dB nHL刺激强度下高于对照组,差异有统计学意义(P<0.05)。结论高强度刺激下(96 dB nHL)耳蜗电图SP/AP振幅比和面积比对噪声导致的隐性听力损失检测有一定的参考价值。
文摘Duration is a salient feature of acoustic signals including speech. Duration tuning was first reported in frogs and later in echolocating bats. More recently, duration tuning has been reported in non-echolocating mammals and appears to be a fundamental encoding mechanism throughout the animal kingdom. However, the duration tuning reported in these non-echolocating mammals appears to be much weaker than that in the previous studies on bats. In contrast to this finding, our recent study reported that duration tuning in the IC in guinea pigs appeared to be strong when it was measured using an appropriate temporal window. With such a temporal window, duration tuning was found to be compatible with that of echo-locating bats. In the present report, we further demonstrate that duration tuning in the IC of this species is established by interaction between excitation and GABAergic inhibition. In addition to overall increase in responsiveness, application of bicuculline(BIC), a GABA-A receptor antagonist, was found to significantly reduce or eliminate duration selectivity in 44 out of the 67 neurons that showed clear duration tuning from a sample of 340 neurons.
基金supported by the National Basic Research Program of China (Grant Nos. 2011CB504506 and 2007CB512306)the National Natural Science Foundation of China (Grant Nos. 30970977 and 30730041)the Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No. KSCX1-YW-R-36)
文摘Neuronal ion channels of different types often do not function independently but will inhibit or potentiate the activity of other types of channels,a process called cross-talk.The N-methyl-D-aspartate receptor (NMDA receptor) and the γ-aminobutyric acid type A receptor (GABAA receptor) are important excitatory and inhibitory receptors in the central nervous system,respectively.Currently,cross-talk between the NMDA receptor and the GABAA receptor,particularly in the central auditory system,is not well understood.In the present study,we investigated functional interactions between the NMDA receptor and the GABAA receptor using whole-cell patch-clamp techniques in cultured neurons from the inferior colliculus,which is an important nucleus in the central auditory system.We found that the currents induced by aspartate at 100 μmol L-1 were suppressed by the pre-perfusion of GABA at 100 μmol L-1,indicating cross-inhibition of NMDA receptors by activation of GABAA receptors.Moreover,we found that the currents induced by GABA at 100 μmol L-1 (IGABA) were not suppressed by the pre-perfusion of 100 μmol L-1 aspartate,but those induced by GABA at 3 μmol L-1 were suppressed,indicating concentration-dependent cross-inhibition of GABAA receptors by activation of NMDA receptors.In addition,inhibition of IGABA by aspartate was not affected by blockade of voltage-dependent Ca2+ channels with CdCl2 in a solution that contained Ca2+,however,CdCl2 effectively attenuated the inhibition of IGABA by aspartate when it was perfused in a solution that contained Ba2+ instead of Ca2+ or a solution that contained Ca2+ and 10 mmol L-1 BAPTA,a membrane-permeable Ca2+ chelator,suggesting that this inhibition is mediated by Ca2+ influx through NMDA receptors,rather than voltage-dependent Ca2+ channels.Finally,KN-62,a potent inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMKII),reduced the inhibition of IGABA by aspartate,indicating the involvement of CaMKII in this cross-inhibition.Our study demonstrates a functional interaction between NMDA and GABAA receptors in the inferior colliculus of rats.The presence of cross-talk between these receptors suggests that the mechanisms underlying information processing in the central auditory system may be more complex than previously believed.
文摘Background:Complex noise and its relation to hearing loss are difficult to measure and evaluate.In complex noise measurement,individual exposure results may not accurately represent lifetime noise exposure.Thus,the mean LAeq,8 h values of individuals in the same workgroup were also used to represent LAeq,8h in our study.Our study aimed to explore whether the mean exposure levels of workers in the same workgroup represented real noise exposure better than individual exposure levels did.Methods:A cross-sectional study was conducted to establish a model for cumulative noise exposure (CNE) and hearing loss in 205 occupational noise-exposed workers who were recruited from two large automobile manufacturers in China.We used a personal noise dosimeter and a questionnaire to determine the workers' occupational noise exposure levels and exposure times,respectively.A qualified audiologist used standardized audiometric procedures to assess hearing acuity after at least 16 h of noise avoidance.Results:We observed that 88.3％ of workers were exposed to more than 85 dB(A) of occupational noise (mean:89.3 ± 4.2 dB(A)).The personal CNE (CNEp) and workgroup CNE (CNEg) were 100.5 ± 4.7 dB(A) and 100.5 ± 2.9 dB(A),respectively.In the binary logistic regression analysis,we established a regression model with high-frequency hearing loss as the dependent variable and CNE as the independent variable.The Wald value was 5.014 with CNEp as the independent variable and 8.653 with CNEg as the independent variable.Furthermore,we found that the figure for CNEg was more similar to the stationary noise reference than CNEp was.The CNEg model was better than the CNEp model.In this circumstance,we can measure some subjects instead of the whole workgroup and save manpower.Conclusions:In a complex noise environment,the measurements of average noise exposure level of the workgroup can improve the accuracy and save manpower.
基金supported by the National Basic Research Development Program of China(2011CB504506 and2012CB932502)the National Natural Science Foundation of China(81570915,81371503 and 31170965)the Open Fund from CAS Key Laboratory of Brain Function and Diseases,China(2012-3)
文摘Rebound depolarization （RD） is a response to the offset from hyperpolarization of the neuronal mem- brane potential and is an important mechanism for the synaptic processing of inhibitory signals. In the present study, we characterized RD in neurons of the rat medial geniculate body （MGB）, a nucleus of the auditory thala- mus, using whole-cell patch-clamp and brain slices. RD was proportional in strength to the duration and magnitude of the hyperpolarization; was effectively blocked by Ni2＋ or Mibefradil; and was depressed when the resting membrane potential was hyperpolarized by blocking hyperpolarization-activated cyclic nucleotide-gated （HCN） channels with ZD7288 or by activating G-protein-gated inwardly-rectifying K＋ （GIRK） channels with baclofen. Our results demonstrated that RD in MGB neurons, which is carried by T-type Ca2＋ channels, is critically regulated by HCN channels and likely by GIRK channels.
基金Zhejiang Province Key Research and Development Project,China(Grant No.2015C03039)Zhejiang Provincial Program for the Cultivation of High-level Innovative Health Talents,China(Grant No.2016-63-07)+2 种基金Health Commission of Zhejiang Province(Grant No.2019KY057)the Program of Occupational Health Risk Assessment of China NIOHP(Grant No.131031109000160004)and the National Institute for Occupational Safety and Health,USA(Grant No.200-2015-M-63857,Grant No.200-2016-M-91922).
文摘Summary What is already known about this topic?Occupational noise-induced hearing loss(NIHL)has been the second most common occupational disease in China.Noise energy is the main risk factor for occupational NIHL.Evidence shows the temporal structure of noise(as indicated by kurtosis metric)contribute to the development of NIHL.However,the role of the kurtosis metric in evaluating the risk of occupational NIHL associated with complex noise has been rarely reported.
基金National Institute for Occupational Safety and Health,USA(Grant No.200-2015-M-63857,200-2016-M-91922)Zhejiang Province Key Research and Development Project,China(Grant No.2015C03039)+2 种基金Zhejiang Provincial Program for the Cultivation of High-level Innovative Health Talents,China(Grant No,2016-63-07)Program of Occupational Health Risk Assessment of China NIOHP(Grant No.131031109000160004)and Occupational Health Standards Preliminary Research Project of China NIOHP(Grant No.20210102).
文摘It is well known that high-level noise exposure can lead to hearing loss.Noise-induced hearing loss(NIHL)continues to be one of the major occupational health hazards.An underlying assumption in current noise standards,e.g.,ISO 1999:2013(1),is that hearing loss is related to the total energy of the exposure.Thus,the risk of NIHL can be predicted according to the ISO 1999 prediction model.Unfortunately,the validity of the prediction model to correctly predict the NIHL for all types of noise exposure is still under question,especially for complex noise of impulsive character.
