Biochemical markers of bone turnover in benign paroxysmal positional vertigo

by Sun Bin Lee, Chang Ho Lee, Young Ju Kim, Hyoung-Mi Kim

Objective

Several studies have suggested a possible relationship between recurrent benign paroxysmal positional vertigo (BPPV) and altered calcium homeostasis in the endolymph of the inner ear. The present study aimed to evaluate the association between Ca²⁺ and vitamin D status and BPPV occurrence as well as the status of bone biochemical markers in osteoporotic patients who were diagnosed with idiopathic BPPV.

Methods

The study included total 132 patients who were referred to our clinic between August 2008 and October 2013. Based on the bone mineral density (BMD) results, the subjects were divided into three groups: normal BMD (n = 34), osteopenia (n = 40) and osteoporosis (n = 58). The biochemical markers of bone turnover including serum Carboxy-terminal telopeptide of type I collagen (s-CTX), osteocalcin, alkaline phosphatase (ALP) and urinary free deoxypyridinoline (u-DPD), were analyzed, along with the serum Ca²⁺ and vitamin D levels.

Results

The mean serum calcium, phosphate and creatinine clearance levels were within the standard laboratory reference range. The incidence of vitamin D deficiency was 11.8% (4/34) in the normal BMD group, 15% (6/40) in the osteopenia group and 43.1% (25/58) in the osteoporosis group. There was a positive correlation between the 25(OH)D and BMD results in the patients with BPPV. Among the bone turnover markers, the osteocalcin and u-DPD levels were significantly elevated in the osteoporotic patients with BPPV. Multiple logistic regression analyses showed that osteoporosis and vitamin D deficiency were associated with BPPV.

Conclusion

Our findings suggest that the prevalence of BPPV in osteoporotic patients is associated with vitamin D deficiency and high bone turnover rates at systemic level, which could disturb local Ca²⁺ homeostasis in the inner ear.

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Hearing Threshold Shifts Among 11- to 35-Year-Olds With Early Hearing Impairment.

Objectives: Data obtained from the clinical records of selected 11- to 35-year-olds with preadult onset hearing impairment were analyzed with 2 primary aims: (1) to determine the incidence of hearing threshold level (HTL) shift in this cohort and, (2) to examine the relationship between HTL shift, whole-of-life noise exposure, and other factors. Design: Cross-sectional cohort study. Retrospective HTL + survey data for a sample of 237 young Australians receiving hearing (re)habilitation services were obtained. From these data, two subsets, (A) n = 127 and (B) n = 79, were analyzed. Participants with risk factors for progressive hearing loss (other than noise exposure) were excluded from both subsets. Subset (A) additionally excluded cochlear implant recipients, and subset (B) excluded cases with diagnosis of hearing loss after age 5 years. Using subset (A) data, the differences between final (recent) and specified baseline (initial) HTLs at 250, 500, 1000, 2000, and 4000 Hz were calculated and three criteria for HTL shift were applied. Correlations between reported noise exposure and HTL shift were calculated (Mann-Whitney U test). Using subset (B) data, relationships between high frequency (HF) HTL shift and exposure, and other personal and extrinsic factors were examined (Cox Regression model). Survival analyses (Kaplan-Meier) were performed to reveal the temporal pattern of HF shift. The magnitude of HF shifts at 5, 10, and 15 years post initial (i.e., specified baseline) audiogram were also calculated. Results: For subset (A), HTL shift (>=15 dB any frequency, and/or >=10 dB* at two adjacent frequencies) was observed in 46.5% of cases examined. HF shift (>=15 dB at 2000 and/or 4000 Hz; one or both ears) was observed in 33.1% of cases. There was no relationship between HTL shift and reported whole-of-life exposure. For subset (B), no relationship was found between HF shift and noise exposure, nor 9 of 10 personal or extrinsic covariates tested. HF shift was significantly associated with HTL >= 70 dB at 2000 and/or 4000 Hz at initial audiogram. Survival analysis also illustrated that HF shift was more frequent, and occurred earlier, when HF hearing loss was >=70 dB at initial audiogram. Median HF shifts at 15 years after initial audiogram were in the magnitude of 5 to 10 dB, and at the 90th percentile were 25 to 30 dB. Conclusions: HTL shift was observed in almost 50% of cases without predisposing factors for progressive hearing loss. The magnitude of HF shift increased gradually over time. While no relationship was found between HTL shift and noise exposure, the interpretation of this finding is restrained by the small spread of whole-of-life noise exposures, within a relatively conservative range. Nevertheless, this is the first direct examination of the relationship between HTL shift and noise exposure in young people with preadult hearing impairment. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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Reporting Newborn Audiologic Results to State EHDI Programs.

Objectives: All US states and territories have an Early Hearing Detection and Intervention (EHDI) program to facilitate early hearing evaluation and intervention for infants who are deaf or hard of hearing. To ensure efficient coordination of care, the state EHDI programs rely heavily on audiologists' prompt reporting of a newborn's hearing status. Several states have regulations requiring mandatory reporting of a newborn's hearing status. This is an important public health responsibility of pediatric audiologists. Reasons for failing to report vary. Design: The Early Hearing Detection and Intervention-Pediatric Audiology Links to Services (EHDI) facility survey was used to inform reporting compliance of audiology facilities throughout the United States. The survey was disseminated via articles, newsletters, and call-to-action notices to audiologists. Results: Among 1024 facilities surveyed, 88 (8.6%) reported that they did not report newborn's hearing findings to their state EHDI program. Not knowing how to report to the state EHDI program was the most frequently chosen reason (60%). However, among the 936 facilities that were compliant with the reporting requirements, 51 estimated that they reported less than two-third of all hearing evaluation results (5.4%). Some facilities did not report a normal-hearing result and some failed to report because they assumed another facility would report the hearing results. Conclusions: Survey results indicated that audiologists were compliant reporting hearing results to the state EHDI programs. However, there is room for improvement. Regular provider outreach and training by the state EHDI program is necessary to ensure those who are not reporting will comply and to clarify reporting requirements for those who are already compliant. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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Hearing Threshold Shifts Among 11- to 35-Year-Olds With Early Hearing Impairment.

Objectives: Data obtained from the clinical records of selected 11- to 35-year-olds with preadult onset hearing impairment were analyzed with 2 primary aims: (1) to determine the incidence of hearing threshold level (HTL) shift in this cohort and, (2) to examine the relationship between HTL shift, whole-of-life noise exposure, and other factors. Design: Cross-sectional cohort study. Retrospective HTL + survey data for a sample of 237 young Australians receiving hearing (re)habilitation services were obtained. From these data, two subsets, (A) n = 127 and (B) n = 79, were analyzed. Participants with risk factors for progressive hearing loss (other than noise exposure) were excluded from both subsets. Subset (A) additionally excluded cochlear implant recipients, and subset (B) excluded cases with diagnosis of hearing loss after age 5 years. Using subset (A) data, the differences between final (recent) and specified baseline (initial) HTLs at 250, 500, 1000, 2000, and 4000 Hz were calculated and three criteria for HTL shift were applied. Correlations between reported noise exposure and HTL shift were calculated (Mann-Whitney U test). Using subset (B) data, relationships between high frequency (HF) HTL shift and exposure, and other personal and extrinsic factors were examined (Cox Regression model). Survival analyses (Kaplan-Meier) were performed to reveal the temporal pattern of HF shift. The magnitude of HF shifts at 5, 10, and 15 years post initial (i.e., specified baseline) audiogram were also calculated. Results: For subset (A), HTL shift (>=15 dB any frequency, and/or >=10 dB* at two adjacent frequencies) was observed in 46.5% of cases examined. HF shift (>=15 dB at 2000 and/or 4000 Hz; one or both ears) was observed in 33.1% of cases. There was no relationship between HTL shift and reported whole-of-life exposure. For subset (B), no relationship was found between HF shift and noise exposure, nor 9 of 10 personal or extrinsic covariates tested. HF shift was significantly associated with HTL >= 70 dB at 2000 and/or 4000 Hz at initial audiogram. Survival analysis also illustrated that HF shift was more frequent, and occurred earlier, when HF hearing loss was >=70 dB at initial audiogram. Median HF shifts at 15 years after initial audiogram were in the magnitude of 5 to 10 dB, and at the 90th percentile were 25 to 30 dB. Conclusions: HTL shift was observed in almost 50% of cases without predisposing factors for progressive hearing loss. The magnitude of HF shift increased gradually over time. While no relationship was found between HTL shift and noise exposure, the interpretation of this finding is restrained by the small spread of whole-of-life noise exposures, within a relatively conservative range. Nevertheless, this is the first direct examination of the relationship between HTL shift and noise exposure in young people with preadult hearing impairment. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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Reporting Newborn Audiologic Results to State EHDI Programs.

Objectives: All US states and territories have an Early Hearing Detection and Intervention (EHDI) program to facilitate early hearing evaluation and intervention for infants who are deaf or hard of hearing. To ensure efficient coordination of care, the state EHDI programs rely heavily on audiologists' prompt reporting of a newborn's hearing status. Several states have regulations requiring mandatory reporting of a newborn's hearing status. This is an important public health responsibility of pediatric audiologists. Reasons for failing to report vary. Design: The Early Hearing Detection and Intervention-Pediatric Audiology Links to Services (EHDI) facility survey was used to inform reporting compliance of audiology facilities throughout the United States. The survey was disseminated via articles, newsletters, and call-to-action notices to audiologists. Results: Among 1024 facilities surveyed, 88 (8.6%) reported that they did not report newborn's hearing findings to their state EHDI program. Not knowing how to report to the state EHDI program was the most frequently chosen reason (60%). However, among the 936 facilities that were compliant with the reporting requirements, 51 estimated that they reported less than two-third of all hearing evaluation results (5.4%). Some facilities did not report a normal-hearing result and some failed to report because they assumed another facility would report the hearing results. Conclusions: Survey results indicated that audiologists were compliant reporting hearing results to the state EHDI programs. However, there is room for improvement. Regular provider outreach and training by the state EHDI program is necessary to ensure those who are not reporting will comply and to clarify reporting requirements for those who are already compliant. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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Hearing Threshold Shifts Among 11- to 35-Year-Olds With Early Hearing Impairment.

Objectives: Data obtained from the clinical records of selected 11- to 35-year-olds with preadult onset hearing impairment were analyzed with 2 primary aims: (1) to determine the incidence of hearing threshold level (HTL) shift in this cohort and, (2) to examine the relationship between HTL shift, whole-of-life noise exposure, and other factors. Design: Cross-sectional cohort study. Retrospective HTL + survey data for a sample of 237 young Australians receiving hearing (re)habilitation services were obtained. From these data, two subsets, (A) n = 127 and (B) n = 79, were analyzed. Participants with risk factors for progressive hearing loss (other than noise exposure) were excluded from both subsets. Subset (A) additionally excluded cochlear implant recipients, and subset (B) excluded cases with diagnosis of hearing loss after age 5 years. Using subset (A) data, the differences between final (recent) and specified baseline (initial) HTLs at 250, 500, 1000, 2000, and 4000 Hz were calculated and three criteria for HTL shift were applied. Correlations between reported noise exposure and HTL shift were calculated (Mann-Whitney U test). Using subset (B) data, relationships between high frequency (HF) HTL shift and exposure, and other personal and extrinsic factors were examined (Cox Regression model). Survival analyses (Kaplan-Meier) were performed to reveal the temporal pattern of HF shift. The magnitude of HF shifts at 5, 10, and 15 years post initial (i.e., specified baseline) audiogram were also calculated. Results: For subset (A), HTL shift (>=15 dB any frequency, and/or >=10 dB* at two adjacent frequencies) was observed in 46.5% of cases examined. HF shift (>=15 dB at 2000 and/or 4000 Hz; one or both ears) was observed in 33.1% of cases. There was no relationship between HTL shift and reported whole-of-life exposure. For subset (B), no relationship was found between HF shift and noise exposure, nor 9 of 10 personal or extrinsic covariates tested. HF shift was significantly associated with HTL >= 70 dB at 2000 and/or 4000 Hz at initial audiogram. Survival analysis also illustrated that HF shift was more frequent, and occurred earlier, when HF hearing loss was >=70 dB at initial audiogram. Median HF shifts at 15 years after initial audiogram were in the magnitude of 5 to 10 dB, and at the 90th percentile were 25 to 30 dB. Conclusions: HTL shift was observed in almost 50% of cases without predisposing factors for progressive hearing loss. The magnitude of HF shift increased gradually over time. While no relationship was found between HTL shift and noise exposure, the interpretation of this finding is restrained by the small spread of whole-of-life noise exposures, within a relatively conservative range. Nevertheless, this is the first direct examination of the relationship between HTL shift and noise exposure in young people with preadult hearing impairment. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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Reporting Newborn Audiologic Results to State EHDI Programs.

Objectives: All US states and territories have an Early Hearing Detection and Intervention (EHDI) program to facilitate early hearing evaluation and intervention for infants who are deaf or hard of hearing. To ensure efficient coordination of care, the state EHDI programs rely heavily on audiologists' prompt reporting of a newborn's hearing status. Several states have regulations requiring mandatory reporting of a newborn's hearing status. This is an important public health responsibility of pediatric audiologists. Reasons for failing to report vary. Design: The Early Hearing Detection and Intervention-Pediatric Audiology Links to Services (EHDI) facility survey was used to inform reporting compliance of audiology facilities throughout the United States. The survey was disseminated via articles, newsletters, and call-to-action notices to audiologists. Results: Among 1024 facilities surveyed, 88 (8.6%) reported that they did not report newborn's hearing findings to their state EHDI program. Not knowing how to report to the state EHDI program was the most frequently chosen reason (60%). However, among the 936 facilities that were compliant with the reporting requirements, 51 estimated that they reported less than two-third of all hearing evaluation results (5.4%). Some facilities did not report a normal-hearing result and some failed to report because they assumed another facility would report the hearing results. Conclusions: Survey results indicated that audiologists were compliant reporting hearing results to the state EHDI programs. However, there is room for improvement. Regular provider outreach and training by the state EHDI program is necessary to ensure those who are not reporting will comply and to clarify reporting requirements for those who are already compliant. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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Growing Ears

Recently, researchers from Indiana University and Harvard established a method for developing human inner ear organoids in 3D culture. As described in Nature Biotechnology (Koehler et al., 2017), differentiated human pluripotent stem cells into an inner ear-like organ (organoid) with functional hair cells. The advantage of this approach is the use of human cells that are different from animal models.

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Celebrities Tinnitus

Dealing with tinnitus can be difficult. Many people who suffer from tinnitus feel as though they are alone. However, there are many celebrities who suffer from this problem. Reading about celebrities tinnitus can make you feel better about your condition.

Gerald Butler

Gerald Butler is a Scottish actor who has been in the acting business for several years. He is one of the celebrities tinnitus. Gerald was diagnosed with tinnitus when he was 10-years-old. He is also partially-deaf in his right ear. However, he was determined to not let his conditions keep him down.

Chris Johns

Chris Johns is a singer, songwriter and a member of the band Coldplay. He was diagnosed with tinnitus over 10 years ago. He stated that he believes listening to loud music contributed to his condition. He now protects his ears with plugs in order to prevent his condition from getting worse. He wishes he would have done this earlier in his life.

Jeff Beck

Jeff Beck is a rock guitarist. He is also another one of the celebrities tinnitus. He stated in an interview with “Rolling Stone” that the condition is excruciating. He also stated that the condition never goes away. In fact, he had to cancel a performance in 1993 because of his tinnitus. Jeff has had setbacks because of his condition, but he has not let it stop him from pursuing his passion. He has won several Grammy awards and continues to perform.

Ayumi Hamasaki

Ayumi Hamasaki is a Japanese celebrity. She is an actress, songwriter and musician. In 2008, she wrote about tinnitus on her blog. She had known that something was wrong with her hearing ever since 2000. She was officially diagnosed with tinnitus in 2006. Ayumi finds it difficult to perform at times because of her condition. However, she works hard so that she does not disappoint herself or her fans.

Steve Martin

Steve Martin is a comedian and actor. He developed tinnitus while he was working on “Three Amigos.” He believes that his tinnitus was caused by a gunshot sound.

William Shatner

William Shatner is an actor who has been on television and in movies for over 50 years. He was diagnosed with tinnitus after an on-set accident. He has stated that his tinnitus is both a blessing and a curse. William has committed a lot of his time to help raise awareness about the disorder. He is involved with the American Tinnitus Association.

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Acuity in ranging based on delay-tuned combination-sensitive neurons in the auditory cortex of mustached bats

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Masakiyo Suzuki, Nobuo Suga
A 1.0-ms echo delay from an emitted bio-sonar pulse at 25 °C corresponds to a 17.3-cm target distance. In the auditory cortex of the mustached bat, Pteronotus parnellii, neurons tuned to a specific delay (best delay) of an echo from an emitted pulse are clustered in the FF, dorsal fringe and ventral fringe areas. (“FF” stands for the frequency-modulated components of a pulse and its echo.) Those delay-tuned neurons are systematically arranged in the FF area according to their best delays and form a 18-ms-long delay axis. Using the neurophysiological data, the theoretical acuity at a 75% correct level was computed as just-noticeable changes in (a) the location of maximally responding delay-tuned neurons, (b) the location of the center of all responses in the FF area, and (c) the weighted sum of responses of all delay-tuned neurons. The acuity is range-dependent: the shorter the target range, the higher the acuity is. The just-noticeable changes in target range are 7.57–46.2, 0.50–2.32 and 0.22–2.53 mm at the target ranges of up to 140 cm for (a), (b) and (c), respectively. When the dorsal and ventral fringe areas are included in the computation, the just-noticeable changes become smaller than those in the FF area alone. Those acuities computed are comparable to certain behavioral acuities.



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Effect of efferent activation on binaural frequency selectivity

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Jesko L. Verhey, Monika Kordus, Vit Drga, Ifat Yasin
Binaural notched-noise experiments indicate a reduced frequency selectivity of the binaural system compared to monaural processing. The present study investigates how auditory efferent activation (via the medial olivocochlear system) affects binaural frequency selectivity in normal-hearing listeners. Thresholds were measured for a 1-kHz signal embedded in a diotic notched-noise masker for various notch widths. The signal was either presented in phase (diotic) or in antiphase (dichotic), gated with the noise. Stimulus duration was 25 ms, in order to avoid efferent activation due to the masker or the signal. A bandpass-filtered noise precursor was presented prior to the masker and signal stimuli to activate the efferent system. The silent interval between the precursor and the masker-signal complex was 50 ms. For comparison, thresholds for detectability of the masked signal were also measured in a baseline condition without the precursor and, in addition, without the masker. On average, the results of the baseline condition indicate an effectively wider binaural filter, as expected. For both signal phases, the addition of the precursor results in effectively wider filters, which is in agreement with the hypothesis that cochlear gain is reduced due to the presence of the precursor.



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Chronic tinnitus and unipolar brush cell alterations in the cerebellum and dorsal cochlear nucleus

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Thomas Brozoski, Daniel Brozoski, Kurt Wisner, Carol Bauer
Animal model research has shown that the central features of tinnitus, the perception of sound without an acoustic correlate, include elevated spontaneous and stimulus-driven activity, enhanced burst-mode firing, decreased variance of inter-spike intervals, and distortion of tonotopic frequency representation. Less well documented are cell-specific correlates of tinnitus. Unipolar brush cell (UBC) alterations in animals with psychophysical evidence of tinnitus has recently been reported. UBCs are glutamatergic interneurons that appear to function as local-circuit signal amplifiers. UBCs are abundant in the dorsal cochlear nucleus (DCN) and very abundant in the flocculus (FL) and paraflocculus (PFL) of the cerebellum. In the present research, two indicators of UBC structure and function were examined: Doublecortin (DCX) and epidermal growth factor receptor substrate 8 (Eps8). DCX is a protein that binds to microtubules where it can modify their assembly and growth. Eps8 is a cell-surface tyrosine kinase receptor mediating the response to epidermal growth factor; it appears to have a role in actin polymerization as well as cytoskeletal protein interactions. Both functions could contribute to synaptic remodeling. In the present research UBC Eps8 and DCX immunoreactivity (IR) were determined in 4 groups of rats distinguished by their exposure to high-level sound and psychophysical performance: Unexposed, exposed to high-level sound with behavioral evidence of tinnitus, and two exposed groups without behavioral evidence of tinnitus. Compared to unexposed controls, exposed animals with tinnitus had Eps8 IR elevated in their PFL; other structures were not affected, nor was DCX IR affected. This was interpreted as UBC upregulation in animals with tinnitus. Exposure that failed to produce tinnitus did not increase either Eps8 or DCX IR. Rather Eps8 IR was decreased in the FL and DCN of one subgroup (Least-Tinnitus), while DCX IR decreased in the FL of the other subgroup (No-Tinnitus). Neuron degeneration was also documented in the cochlear nucleus and PFL of exposed animals, both with and without tinnitus. Degeneration was not found in unexposed animals. Implications for tinnitus neuropathy are discussed in the context of synaptic remodeling and cerebellar sensory modulation.



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Acuity in ranging based on delay-tuned combination-sensitive neurons in the auditory cortex of mustached bats

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Masakiyo Suzuki, Nobuo Suga
A 1.0-ms echo delay from an emitted bio-sonar pulse at 25 °C corresponds to a 17.3-cm target distance. In the auditory cortex of the mustached bat, Pteronotus parnellii, neurons tuned to a specific delay (best delay) of an echo from an emitted pulse are clustered in the FF, dorsal fringe and ventral fringe areas. (“FF” stands for the frequency-modulated components of a pulse and its echo.) Those delay-tuned neurons are systematically arranged in the FF area according to their best delays and form a 18-ms-long delay axis. Using the neurophysiological data, the theoretical acuity at a 75% correct level was computed as just-noticeable changes in (a) the location of maximally responding delay-tuned neurons, (b) the location of the center of all responses in the FF area, and (c) the weighted sum of responses of all delay-tuned neurons. The acuity is range-dependent: the shorter the target range, the higher the acuity is. The just-noticeable changes in target range are 7.57–46.2, 0.50–2.32 and 0.22–2.53 mm at the target ranges of up to 140 cm for (a), (b) and (c), respectively. When the dorsal and ventral fringe areas are included in the computation, the just-noticeable changes become smaller than those in the FF area alone. Those acuities computed are comparable to certain behavioral acuities.



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Effect of efferent activation on binaural frequency selectivity

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Jesko L. Verhey, Monika Kordus, Vit Drga, Ifat Yasin
Binaural notched-noise experiments indicate a reduced frequency selectivity of the binaural system compared to monaural processing. The present study investigates how auditory efferent activation (via the medial olivocochlear system) affects binaural frequency selectivity in normal-hearing listeners. Thresholds were measured for a 1-kHz signal embedded in a diotic notched-noise masker for various notch widths. The signal was either presented in phase (diotic) or in antiphase (dichotic), gated with the noise. Stimulus duration was 25 ms, in order to avoid efferent activation due to the masker or the signal. A bandpass-filtered noise precursor was presented prior to the masker and signal stimuli to activate the efferent system. The silent interval between the precursor and the masker-signal complex was 50 ms. For comparison, thresholds for detectability of the masked signal were also measured in a baseline condition without the precursor and, in addition, without the masker. On average, the results of the baseline condition indicate an effectively wider binaural filter, as expected. For both signal phases, the addition of the precursor results in effectively wider filters, which is in agreement with the hypothesis that cochlear gain is reduced due to the presence of the precursor.



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Chronic tinnitus and unipolar brush cell alterations in the cerebellum and dorsal cochlear nucleus

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Thomas Brozoski, Daniel Brozoski, Kurt Wisner, Carol Bauer
Animal model research has shown that the central features of tinnitus, the perception of sound without an acoustic correlate, include elevated spontaneous and stimulus-driven activity, enhanced burst-mode firing, decreased variance of inter-spike intervals, and distortion of tonotopic frequency representation. Less well documented are cell-specific correlates of tinnitus. Unipolar brush cell (UBC) alterations in animals with psychophysical evidence of tinnitus has recently been reported. UBCs are glutamatergic interneurons that appear to function as local-circuit signal amplifiers. UBCs are abundant in the dorsal cochlear nucleus (DCN) and very abundant in the flocculus (FL) and paraflocculus (PFL) of the cerebellum. In the present research, two indicators of UBC structure and function were examined: Doublecortin (DCX) and epidermal growth factor receptor substrate 8 (Eps8). DCX is a protein that binds to microtubules where it can modify their assembly and growth. Eps8 is a cell-surface tyrosine kinase receptor mediating the response to epidermal growth factor; it appears to have a role in actin polymerization as well as cytoskeletal protein interactions. Both functions could contribute to synaptic remodeling. In the present research UBC Eps8 and DCX immunoreactivity (IR) were determined in 4 groups of rats distinguished by their exposure to high-level sound and psychophysical performance: Unexposed, exposed to high-level sound with behavioral evidence of tinnitus, and two exposed groups without behavioral evidence of tinnitus. Compared to unexposed controls, exposed animals with tinnitus had Eps8 IR elevated in their PFL; other structures were not affected, nor was DCX IR affected. This was interpreted as UBC upregulation in animals with tinnitus. Exposure that failed to produce tinnitus did not increase either Eps8 or DCX IR. Rather Eps8 IR was decreased in the FL and DCN of one subgroup (Least-Tinnitus), while DCX IR decreased in the FL of the other subgroup (No-Tinnitus). Neuron degeneration was also documented in the cochlear nucleus and PFL of exposed animals, both with and without tinnitus. Degeneration was not found in unexposed animals. Implications for tinnitus neuropathy are discussed in the context of synaptic remodeling and cerebellar sensory modulation.



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Acuity in ranging based on delay-tuned combination-sensitive neurons in the auditory cortex of mustached bats

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Masakiyo Suzuki, Nobuo Suga
A 1.0-ms echo delay from an emitted bio-sonar pulse at 25 °C corresponds to a 17.3-cm target distance. In the auditory cortex of the mustached bat, Pteronotus parnellii, neurons tuned to a specific delay (best delay) of an echo from an emitted pulse are clustered in the FF, dorsal fringe and ventral fringe areas. (“FF” stands for the frequency-modulated components of a pulse and its echo.) Those delay-tuned neurons are systematically arranged in the FF area according to their best delays and form a 18-ms-long delay axis. Using the neurophysiological data, the theoretical acuity at a 75% correct level was computed as just-noticeable changes in (a) the location of maximally responding delay-tuned neurons, (b) the location of the center of all responses in the FF area, and (c) the weighted sum of responses of all delay-tuned neurons. The acuity is range-dependent: the shorter the target range, the higher the acuity is. The just-noticeable changes in target range are 7.57–46.2, 0.50–2.32 and 0.22–2.53 mm at the target ranges of up to 140 cm for (a), (b) and (c), respectively. When the dorsal and ventral fringe areas are included in the computation, the just-noticeable changes become smaller than those in the FF area alone. Those acuities computed are comparable to certain behavioral acuities.



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Effect of efferent activation on binaural frequency selectivity

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Jesko L. Verhey, Monika Kordus, Vit Drga, Ifat Yasin
Binaural notched-noise experiments indicate a reduced frequency selectivity of the binaural system compared to monaural processing. The present study investigates how auditory efferent activation (via the medial olivocochlear system) affects binaural frequency selectivity in normal-hearing listeners. Thresholds were measured for a 1-kHz signal embedded in a diotic notched-noise masker for various notch widths. The signal was either presented in phase (diotic) or in antiphase (dichotic), gated with the noise. Stimulus duration was 25 ms, in order to avoid efferent activation due to the masker or the signal. A bandpass-filtered noise precursor was presented prior to the masker and signal stimuli to activate the efferent system. The silent interval between the precursor and the masker-signal complex was 50 ms. For comparison, thresholds for detectability of the masked signal were also measured in a baseline condition without the precursor and, in addition, without the masker. On average, the results of the baseline condition indicate an effectively wider binaural filter, as expected. For both signal phases, the addition of the precursor results in effectively wider filters, which is in agreement with the hypothesis that cochlear gain is reduced due to the presence of the precursor.



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Chronic tinnitus and unipolar brush cell alterations in the cerebellum and dorsal cochlear nucleus

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Thomas Brozoski, Daniel Brozoski, Kurt Wisner, Carol Bauer
Animal model research has shown that the central features of tinnitus, the perception of sound without an acoustic correlate, include elevated spontaneous and stimulus-driven activity, enhanced burst-mode firing, decreased variance of inter-spike intervals, and distortion of tonotopic frequency representation. Less well documented are cell-specific correlates of tinnitus. Unipolar brush cell (UBC) alterations in animals with psychophysical evidence of tinnitus has recently been reported. UBCs are glutamatergic interneurons that appear to function as local-circuit signal amplifiers. UBCs are abundant in the dorsal cochlear nucleus (DCN) and very abundant in the flocculus (FL) and paraflocculus (PFL) of the cerebellum. In the present research, two indicators of UBC structure and function were examined: Doublecortin (DCX) and epidermal growth factor receptor substrate 8 (Eps8). DCX is a protein that binds to microtubules where it can modify their assembly and growth. Eps8 is a cell-surface tyrosine kinase receptor mediating the response to epidermal growth factor; it appears to have a role in actin polymerization as well as cytoskeletal protein interactions. Both functions could contribute to synaptic remodeling. In the present research UBC Eps8 and DCX immunoreactivity (IR) were determined in 4 groups of rats distinguished by their exposure to high-level sound and psychophysical performance: Unexposed, exposed to high-level sound with behavioral evidence of tinnitus, and two exposed groups without behavioral evidence of tinnitus. Compared to unexposed controls, exposed animals with tinnitus had Eps8 IR elevated in their PFL; other structures were not affected, nor was DCX IR affected. This was interpreted as UBC upregulation in animals with tinnitus. Exposure that failed to produce tinnitus did not increase either Eps8 or DCX IR. Rather Eps8 IR was decreased in the FL and DCN of one subgroup (Least-Tinnitus), while DCX IR decreased in the FL of the other subgroup (No-Tinnitus). Neuron degeneration was also documented in the cochlear nucleus and PFL of exposed animals, both with and without tinnitus. Degeneration was not found in unexposed animals. Implications for tinnitus neuropathy are discussed in the context of synaptic remodeling and cerebellar sensory modulation.



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Acuity in ranging based on delay-tuned combination-sensitive neurons in the auditory cortex of mustached bats

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Masakiyo Suzuki, Nobuo Suga
A 1.0-ms echo delay from an emitted bio-sonar pulse at 25 °C corresponds to a 17.3-cm target distance. In the auditory cortex of the mustached bat, Pteronotus parnellii, neurons tuned to a specific delay (best delay) of an echo from an emitted pulse are clustered in the FF, dorsal fringe and ventral fringe areas. (“FF” stands for the frequency-modulated components of a pulse and its echo.) Those delay-tuned neurons are systematically arranged in the FF area according to their best delays and form a 18-ms-long delay axis. Using the neurophysiological data, the theoretical acuity at a 75% correct level was computed as just-noticeable changes in (a) the location of maximally responding delay-tuned neurons, (b) the location of the center of all responses in the FF area, and (c) the weighted sum of responses of all delay-tuned neurons. The acuity is range-dependent: the shorter the target range, the higher the acuity is. The just-noticeable changes in target range are 7.57–46.2, 0.50–2.32 and 0.22–2.53 mm at the target ranges of up to 140 cm for (a), (b) and (c), respectively. When the dorsal and ventral fringe areas are included in the computation, the just-noticeable changes become smaller than those in the FF area alone. Those acuities computed are comparable to certain behavioral acuities.



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Effect of efferent activation on binaural frequency selectivity

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Jesko L. Verhey, Monika Kordus, Vit Drga, Ifat Yasin
Binaural notched-noise experiments indicate a reduced frequency selectivity of the binaural system compared to monaural processing. The present study investigates how auditory efferent activation (via the medial olivocochlear system) affects binaural frequency selectivity in normal-hearing listeners. Thresholds were measured for a 1-kHz signal embedded in a diotic notched-noise masker for various notch widths. The signal was either presented in phase (diotic) or in antiphase (dichotic), gated with the noise. Stimulus duration was 25 ms, in order to avoid efferent activation due to the masker or the signal. A bandpass-filtered noise precursor was presented prior to the masker and signal stimuli to activate the efferent system. The silent interval between the precursor and the masker-signal complex was 50 ms. For comparison, thresholds for detectability of the masked signal were also measured in a baseline condition without the precursor and, in addition, without the masker. On average, the results of the baseline condition indicate an effectively wider binaural filter, as expected. For both signal phases, the addition of the precursor results in effectively wider filters, which is in agreement with the hypothesis that cochlear gain is reduced due to the presence of the precursor.



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Chronic tinnitus and unipolar brush cell alterations in the cerebellum and dorsal cochlear nucleus

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Thomas Brozoski, Daniel Brozoski, Kurt Wisner, Carol Bauer
Animal model research has shown that the central features of tinnitus, the perception of sound without an acoustic correlate, include elevated spontaneous and stimulus-driven activity, enhanced burst-mode firing, decreased variance of inter-spike intervals, and distortion of tonotopic frequency representation. Less well documented are cell-specific correlates of tinnitus. Unipolar brush cell (UBC) alterations in animals with psychophysical evidence of tinnitus has recently been reported. UBCs are glutamatergic interneurons that appear to function as local-circuit signal amplifiers. UBCs are abundant in the dorsal cochlear nucleus (DCN) and very abundant in the flocculus (FL) and paraflocculus (PFL) of the cerebellum. In the present research, two indicators of UBC structure and function were examined: Doublecortin (DCX) and epidermal growth factor receptor substrate 8 (Eps8). DCX is a protein that binds to microtubules where it can modify their assembly and growth. Eps8 is a cell-surface tyrosine kinase receptor mediating the response to epidermal growth factor; it appears to have a role in actin polymerization as well as cytoskeletal protein interactions. Both functions could contribute to synaptic remodeling. In the present research UBC Eps8 and DCX immunoreactivity (IR) were determined in 4 groups of rats distinguished by their exposure to high-level sound and psychophysical performance: Unexposed, exposed to high-level sound with behavioral evidence of tinnitus, and two exposed groups without behavioral evidence of tinnitus. Compared to unexposed controls, exposed animals with tinnitus had Eps8 IR elevated in their PFL; other structures were not affected, nor was DCX IR affected. This was interpreted as UBC upregulation in animals with tinnitus. Exposure that failed to produce tinnitus did not increase either Eps8 or DCX IR. Rather Eps8 IR was decreased in the FL and DCN of one subgroup (Least-Tinnitus), while DCX IR decreased in the FL of the other subgroup (No-Tinnitus). Neuron degeneration was also documented in the cochlear nucleus and PFL of exposed animals, both with and without tinnitus. Degeneration was not found in unexposed animals. Implications for tinnitus neuropathy are discussed in the context of synaptic remodeling and cerebellar sensory modulation.



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Acuity in ranging based on delay-tuned combination-sensitive neurons in the auditory cortex of mustached bats

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Masakiyo Suzuki, Nobuo Suga
A 1.0-ms echo delay from an emitted bio-sonar pulse at 25 °C corresponds to a 17.3-cm target distance. In the auditory cortex of the mustached bat, Pteronotus parnellii, neurons tuned to a specific delay (best delay) of an echo from an emitted pulse are clustered in the FF, dorsal fringe and ventral fringe areas. (“FF” stands for the frequency-modulated components of a pulse and its echo.) Those delay-tuned neurons are systematically arranged in the FF area according to their best delays and form a 18-ms-long delay axis. Using the neurophysiological data, the theoretical acuity at a 75% correct level was computed as just-noticeable changes in (a) the location of maximally responding delay-tuned neurons, (b) the location of the center of all responses in the FF area, and (c) the weighted sum of responses of all delay-tuned neurons. The acuity is range-dependent: the shorter the target range, the higher the acuity is. The just-noticeable changes in target range are 7.57–46.2, 0.50–2.32 and 0.22–2.53 mm at the target ranges of up to 140 cm for (a), (b) and (c), respectively. When the dorsal and ventral fringe areas are included in the computation, the just-noticeable changes become smaller than those in the FF area alone. Those acuities computed are comparable to certain behavioral acuities.



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Effect of efferent activation on binaural frequency selectivity

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Jesko L. Verhey, Monika Kordus, Vit Drga, Ifat Yasin
Binaural notched-noise experiments indicate a reduced frequency selectivity of the binaural system compared to monaural processing. The present study investigates how auditory efferent activation (via the medial olivocochlear system) affects binaural frequency selectivity in normal-hearing listeners. Thresholds were measured for a 1-kHz signal embedded in a diotic notched-noise masker for various notch widths. The signal was either presented in phase (diotic) or in antiphase (dichotic), gated with the noise. Stimulus duration was 25 ms, in order to avoid efferent activation due to the masker or the signal. A bandpass-filtered noise precursor was presented prior to the masker and signal stimuli to activate the efferent system. The silent interval between the precursor and the masker-signal complex was 50 ms. For comparison, thresholds for detectability of the masked signal were also measured in a baseline condition without the precursor and, in addition, without the masker. On average, the results of the baseline condition indicate an effectively wider binaural filter, as expected. For both signal phases, the addition of the precursor results in effectively wider filters, which is in agreement with the hypothesis that cochlear gain is reduced due to the presence of the precursor.



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Chronic tinnitus and unipolar brush cell alterations in the cerebellum and dorsal cochlear nucleus

Publication date: Available online 2 May 2017
Source:Hearing Research
Author(s): Thomas Brozoski, Daniel Brozoski, Kurt Wisner, Carol Bauer
Animal model research has shown that the central features of tinnitus, the perception of sound without an acoustic correlate, include elevated spontaneous and stimulus-driven activity, enhanced burst-mode firing, decreased variance of inter-spike intervals, and distortion of tonotopic frequency representation. Less well documented are cell-specific correlates of tinnitus. Unipolar brush cell (UBC) alterations in animals with psychophysical evidence of tinnitus has recently been reported. UBCs are glutamatergic interneurons that appear to function as local-circuit signal amplifiers. UBCs are abundant in the dorsal cochlear nucleus (DCN) and very abundant in the flocculus (FL) and paraflocculus (PFL) of the cerebellum. In the present research, two indicators of UBC structure and function were examined: Doublecortin (DCX) and epidermal growth factor receptor substrate 8 (Eps8). DCX is a protein that binds to microtubules where it can modify their assembly and growth. Eps8 is a cell-surface tyrosine kinase receptor mediating the response to epidermal growth factor; it appears to have a role in actin polymerization as well as cytoskeletal protein interactions. Both functions could contribute to synaptic remodeling. In the present research UBC Eps8 and DCX immunoreactivity (IR) were determined in 4 groups of rats distinguished by their exposure to high-level sound and psychophysical performance: Unexposed, exposed to high-level sound with behavioral evidence of tinnitus, and two exposed groups without behavioral evidence of tinnitus. Compared to unexposed controls, exposed animals with tinnitus had Eps8 IR elevated in their PFL; other structures were not affected, nor was DCX IR affected. This was interpreted as UBC upregulation in animals with tinnitus. Exposure that failed to produce tinnitus did not increase either Eps8 or DCX IR. Rather Eps8 IR was decreased in the FL and DCN of one subgroup (Least-Tinnitus), while DCX IR decreased in the FL of the other subgroup (No-Tinnitus). Neuron degeneration was also documented in the cochlear nucleus and PFL of exposed animals, both with and without tinnitus. Degeneration was not found in unexposed animals. Implications for tinnitus neuropathy are discussed in the context of synaptic remodeling and cerebellar sensory modulation.



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Quantifying sources of variability in gait analysis

Publication date: Available online 3 May 2017
Source:Gait & Posture
Author(s): Kohleth Chia, Morgan Sangeux
Measurements from gait analysis are affected by many sources of variability. Schwartz et al. [1] illustrated an experimental design and methods to estimate these variance components. However, the derivation contains errors which could severely bias the estimation of some components. Therefore, in this paper, we presented correction to this method using ANOVA and Likelihood methods. Furthermore, we demonstrated how commonly used reliability indices like CMC and ICC may be derived from the variance components. We advocate the use of the variance components, in preference to reliability indices, because the variance components are easier to interpret, with understandable units.



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Quantifying sources of variability in gait analysis

Publication date: Available online 3 May 2017
Source:Gait & Posture
Author(s): Kohleth Chia, Morgan Sangeux
Measurements from gait analysis are affected by many sources of variability. Schwartz et al. [1] illustrated an experimental design and methods to estimate these variance components. However, the derivation contains errors which could severely bias the estimation of some components. Therefore, in this paper, we presented correction to this method using ANOVA and Likelihood methods. Furthermore, we demonstrated how commonly used reliability indices like CMC and ICC may be derived from the variance components. We advocate the use of the variance components, in preference to reliability indices, because the variance components are easier to interpret, with understandable units.



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Quantifying sources of variability in gait analysis

Publication date: Available online 3 May 2017
Source:Gait & Posture
Author(s): Kohleth Chia, Morgan Sangeux
Measurements from gait analysis are affected by many sources of variability. Schwartz et al. [1] illustrated an experimental design and methods to estimate these variance components. However, the derivation contains errors which could severely bias the estimation of some components. Therefore, in this paper, we presented correction to this method using ANOVA and Likelihood methods. Furthermore, we demonstrated how commonly used reliability indices like CMC and ICC may be derived from the variance components. We advocate the use of the variance components, in preference to reliability indices, because the variance components are easier to interpret, with understandable units.



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