Publication date: Available online 25 December 2015
Source:Hearing Research
Author(s): Anna-Karin Strömberg, Åke Olofsson, Magnus Westin, Maoli Duan, Stefan Stenfelt
Evaluation of cervical evoked myogenic potentials (c-VEMP) is commonly applied in clinical investigations of patients with suspected neurotological symptoms. Short intense acoustic stimulation of peak levels close to 130 dB SPL is required to elicit the responses. A recent publication on bilateral significant sensorineural hearing loss related to extensive VEMP stimulation motivates evaluations of immediate effects on hearing acuity related to the intense acoustic stimulation required to elicit c-VEMP responses. The aim of the current study was to investigate changes in DPOAE-levels and hearing thresholds in relation to c-VEMP testing in humans. More specifically, the current focus is on immediate changes in hearing thresholds and changes in DPOAE-levels at frequencies 0.5 octaves above the acoustic stimulation when applying shorter tone bursts than previously used. Hearing acuity before and immediately after exposure to c-VEMP stimulation was examined in 24 patients with normal hearing and referred for neurotologic testing. The stimulation consisted of 192 tonebursts of 6 milliseconds and was presented at 500 Hz and 130 dB peSPL. Békésy thresholds at 0.125 to 8 kHz and DPOAE I/O growth functions with stimulation at 0.75 and 3 kHz were used to assess c-VEMP related changes in hearing status. No significant deterioration in Békésy thresholds was detected. Significant reduction in DPOAE levels at 0.75 (0.5-1.35 dB) and 3 kHz (1.6-2.1 dB) was observed after c-VEMP stimulation without concomitant changes in cochlear compression. The results indicated that there was no immediate audiometric loss related to c-VEMP stimulation in the current group of patients. The significant reduction of DPOAE levels at a wider frequency range than previously described after the c-VEMP test could be related to the stimulation with shorter tone bursts. The results show that c-VEMP stimulation causes reduction in DPOAE-levels at several frequencies that corresponds to half the reductions in DPOAE levels reported after exposure to the maximally allowed occupational noise for an eight hours working day. Consequently, extended stimuli intensity or stimulation repetition with c-VEMP testing should be avoided to reduce the risk for noise-induced cochlear injury.
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Παρασκευή 25 Δεκεμβρίου 2015
Influence of the paraflocculus on normal and abnormal spontaneous firing rates in the inferior colliculus
Publication date: Available online 25 December 2015
Source:Hearing Research
Author(s): Darryl P. Vogler, Donald Robertson, Wilhelmina H.A.M. Mulders
Spontaneous firing rates of neurons in the central auditory pathway, such as in the inferior colliculus, are known to be increased after cochlear trauma. This so-called hyperactivity is thought to be involved in the generation of tinnitus, a phantom auditory perception. Recent research in an animal model suggests behavioural signs of tinnitus can be significantly reduced by silencing or removal of the paraflocculus (PF) of the cerebellum. The current study investigated the effects of acute PF removal on spontaneous firing rates recorded from single neurons in the right inferior colliculus of guinea pigs with normal hearing (which did not receive acoustic trauma) or with hearing loss caused by acoustic trauma. Spontaneous firing rates were obtained at either 2 or 13 weeks after initial surgery on the left side. In half of the animals in each group the left PF was removed immediately prior to the spontaneous firing rates recordings. In the acoustic trauma groups, spontaneous firing rates in the inferior colliculus were higher when the PF was removed compared to animals with an intact PF. This effect of PF removal was not observed in animals that did not receive acoustic trauma. These results suggest that the PF has a tonic inhibitory effect on hyperactivity in the inferior colliculus in animals with hearing loss, but not on normal spontaneous firing rates in normal hearing animals.
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Source:Hearing Research
Author(s): Darryl P. Vogler, Donald Robertson, Wilhelmina H.A.M. Mulders
Spontaneous firing rates of neurons in the central auditory pathway, such as in the inferior colliculus, are known to be increased after cochlear trauma. This so-called hyperactivity is thought to be involved in the generation of tinnitus, a phantom auditory perception. Recent research in an animal model suggests behavioural signs of tinnitus can be significantly reduced by silencing or removal of the paraflocculus (PF) of the cerebellum. The current study investigated the effects of acute PF removal on spontaneous firing rates recorded from single neurons in the right inferior colliculus of guinea pigs with normal hearing (which did not receive acoustic trauma) or with hearing loss caused by acoustic trauma. Spontaneous firing rates were obtained at either 2 or 13 weeks after initial surgery on the left side. In half of the animals in each group the left PF was removed immediately prior to the spontaneous firing rates recordings. In the acoustic trauma groups, spontaneous firing rates in the inferior colliculus were higher when the PF was removed compared to animals with an intact PF. This effect of PF removal was not observed in animals that did not receive acoustic trauma. These results suggest that the PF has a tonic inhibitory effect on hyperactivity in the inferior colliculus in animals with hearing loss, but not on normal spontaneous firing rates in normal hearing animals.
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Cortical and thalamic connectivity of the auditory anterior ectosylvian cortex of early-deaf cats: Implications for neural mechanisms of crossmodal plasticity
Publication date: Available online 24 December 2015
Source:Hearing Research
Author(s): M. Alex Meredith, H. Ruth Clemo, Sarah B. Corley, Nicole Chabot, Stephen G. Lomber
Early hearing loss leads to crossmodal plasticity in regions of the cerebrum that are dominated by acoustical processing in hearing subjects. Until recently, little has been known of the connectional basis of this phenomenon. One region whose crossmodal properties are well-established is the auditory field of the anterior ectosylvian sulcus (FAES) in the cat, where neurons are normally responsive to acoustic stimulation and its deactivation leads to the behavioral loss of accurate orienting toward auditory stimuli. However, in early-deaf cats, visual responsiveness predominates in the FAES and its deactivation blocks accurate orienting behavior toward visual stimuli. For such crossmodal reorganization to occur, it has been presumed that novel inputs or increased projections from non-auditory cortical areas must be generated, or that existing non-auditory connections were ‘unmasked.’ These possibilities were tested using tracer injections into the FAES of adult cats deafened early in life (and hearing controls), followed by light microscopy to localize retrogradely labeled neurons. Surprisingly, the distribution of cortical and thalamic afferents to the FAES was very similar among early-deaf and hearing animals. No new visual projection sources were identified and visual cortical connections to the FAES were comparable in projection proportions. These results support an alternate theory for the connectional basis for cross-modal plasticity that involves enhanced local branching of existing projection terminals that originate in non-auditory as well as auditory cortices.
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Source:Hearing Research
Author(s): M. Alex Meredith, H. Ruth Clemo, Sarah B. Corley, Nicole Chabot, Stephen G. Lomber
Early hearing loss leads to crossmodal plasticity in regions of the cerebrum that are dominated by acoustical processing in hearing subjects. Until recently, little has been known of the connectional basis of this phenomenon. One region whose crossmodal properties are well-established is the auditory field of the anterior ectosylvian sulcus (FAES) in the cat, where neurons are normally responsive to acoustic stimulation and its deactivation leads to the behavioral loss of accurate orienting toward auditory stimuli. However, in early-deaf cats, visual responsiveness predominates in the FAES and its deactivation blocks accurate orienting behavior toward visual stimuli. For such crossmodal reorganization to occur, it has been presumed that novel inputs or increased projections from non-auditory cortical areas must be generated, or that existing non-auditory connections were ‘unmasked.’ These possibilities were tested using tracer injections into the FAES of adult cats deafened early in life (and hearing controls), followed by light microscopy to localize retrogradely labeled neurons. Surprisingly, the distribution of cortical and thalamic afferents to the FAES was very similar among early-deaf and hearing animals. No new visual projection sources were identified and visual cortical connections to the FAES were comparable in projection proportions. These results support an alternate theory for the connectional basis for cross-modal plasticity that involves enhanced local branching of existing projection terminals that originate in non-auditory as well as auditory cortices.
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Changes in cochlear function related to acoustic stimulation of cervical vestibular evoked myogenic potential stimulation
Publication date: Available online 25 December 2015
Source:Hearing Research
Author(s): Anna-Karin Strömberg, Åke Olofsson, Magnus Westin, Maoli Duan, Stefan Stenfelt
Evaluation of cervical evoked myogenic potentials (c-VEMP) is commonly applied in clinical investigations of patients with suspected neurotological symptoms. Short intense acoustic stimulation of peak levels close to 130 dB SPL is required to elicit the responses. A recent publication on bilateral significant sensorineural hearing loss related to extensive VEMP stimulation motivates evaluations of immediate effects on hearing acuity related to the intense acoustic stimulation required to elicit c-VEMP responses. The aim of the current study was to investigate changes in DPOAE-levels and hearing thresholds in relation to c-VEMP testing in humans. More specifically, the current focus is on immediate changes in hearing thresholds and changes in DPOAE-levels at frequencies 0.5 octaves above the acoustic stimulation when applying shorter tone bursts than previously used. Hearing acuity before and immediately after exposure to c-VEMP stimulation was examined in 24 patients with normal hearing and referred for neurotologic testing. The stimulation consisted of 192 tonebursts of 6 milliseconds and was presented at 500 Hz and 130 dB peSPL. Békésy thresholds at 0.125 to 8 kHz and DPOAE I/O growth functions with stimulation at 0.75 and 3 kHz were used to assess c-VEMP related changes in hearing status. No significant deterioration in Békésy thresholds was detected. Significant reduction in DPOAE levels at 0.75 (0.5-1.35 dB) and 3 kHz (1.6-2.1 dB) was observed after c-VEMP stimulation without concomitant changes in cochlear compression. The results indicated that there was no immediate audiometric loss related to c-VEMP stimulation in the current group of patients. The significant reduction of DPOAE levels at a wider frequency range than previously described after the c-VEMP test could be related to the stimulation with shorter tone bursts. The results show that c-VEMP stimulation causes reduction in DPOAE-levels at several frequencies that corresponds to half the reductions in DPOAE levels reported after exposure to the maximally allowed occupational noise for an eight hours working day. Consequently, extended stimuli intensity or stimulation repetition with c-VEMP testing should be avoided to reduce the risk for noise-induced cochlear injury.
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Source:Hearing Research
Author(s): Anna-Karin Strömberg, Åke Olofsson, Magnus Westin, Maoli Duan, Stefan Stenfelt
Evaluation of cervical evoked myogenic potentials (c-VEMP) is commonly applied in clinical investigations of patients with suspected neurotological symptoms. Short intense acoustic stimulation of peak levels close to 130 dB SPL is required to elicit the responses. A recent publication on bilateral significant sensorineural hearing loss related to extensive VEMP stimulation motivates evaluations of immediate effects on hearing acuity related to the intense acoustic stimulation required to elicit c-VEMP responses. The aim of the current study was to investigate changes in DPOAE-levels and hearing thresholds in relation to c-VEMP testing in humans. More specifically, the current focus is on immediate changes in hearing thresholds and changes in DPOAE-levels at frequencies 0.5 octaves above the acoustic stimulation when applying shorter tone bursts than previously used. Hearing acuity before and immediately after exposure to c-VEMP stimulation was examined in 24 patients with normal hearing and referred for neurotologic testing. The stimulation consisted of 192 tonebursts of 6 milliseconds and was presented at 500 Hz and 130 dB peSPL. Békésy thresholds at 0.125 to 8 kHz and DPOAE I/O growth functions with stimulation at 0.75 and 3 kHz were used to assess c-VEMP related changes in hearing status. No significant deterioration in Békésy thresholds was detected. Significant reduction in DPOAE levels at 0.75 (0.5-1.35 dB) and 3 kHz (1.6-2.1 dB) was observed after c-VEMP stimulation without concomitant changes in cochlear compression. The results indicated that there was no immediate audiometric loss related to c-VEMP stimulation in the current group of patients. The significant reduction of DPOAE levels at a wider frequency range than previously described after the c-VEMP test could be related to the stimulation with shorter tone bursts. The results show that c-VEMP stimulation causes reduction in DPOAE-levels at several frequencies that corresponds to half the reductions in DPOAE levels reported after exposure to the maximally allowed occupational noise for an eight hours working day. Consequently, extended stimuli intensity or stimulation repetition with c-VEMP testing should be avoided to reduce the risk for noise-induced cochlear injury.
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Influence of the paraflocculus on normal and abnormal spontaneous firing rates in the inferior colliculus
Publication date: Available online 25 December 2015
Source:Hearing Research
Author(s): Darryl P. Vogler, Donald Robertson, Wilhelmina H.A.M. Mulders
Spontaneous firing rates of neurons in the central auditory pathway, such as in the inferior colliculus, are known to be increased after cochlear trauma. This so-called hyperactivity is thought to be involved in the generation of tinnitus, a phantom auditory perception. Recent research in an animal model suggests behavioural signs of tinnitus can be significantly reduced by silencing or removal of the paraflocculus (PF) of the cerebellum. The current study investigated the effects of acute PF removal on spontaneous firing rates recorded from single neurons in the right inferior colliculus of guinea pigs with normal hearing (which did not receive acoustic trauma) or with hearing loss caused by acoustic trauma. Spontaneous firing rates were obtained at either 2 or 13 weeks after initial surgery on the left side. In half of the animals in each group the left PF was removed immediately prior to the spontaneous firing rates recordings. In the acoustic trauma groups, spontaneous firing rates in the inferior colliculus were higher when the PF was removed compared to animals with an intact PF. This effect of PF removal was not observed in animals that did not receive acoustic trauma. These results suggest that the PF has a tonic inhibitory effect on hyperactivity in the inferior colliculus in animals with hearing loss, but not on normal spontaneous firing rates in normal hearing animals.
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Source:Hearing Research
Author(s): Darryl P. Vogler, Donald Robertson, Wilhelmina H.A.M. Mulders
Spontaneous firing rates of neurons in the central auditory pathway, such as in the inferior colliculus, are known to be increased after cochlear trauma. This so-called hyperactivity is thought to be involved in the generation of tinnitus, a phantom auditory perception. Recent research in an animal model suggests behavioural signs of tinnitus can be significantly reduced by silencing or removal of the paraflocculus (PF) of the cerebellum. The current study investigated the effects of acute PF removal on spontaneous firing rates recorded from single neurons in the right inferior colliculus of guinea pigs with normal hearing (which did not receive acoustic trauma) or with hearing loss caused by acoustic trauma. Spontaneous firing rates were obtained at either 2 or 13 weeks after initial surgery on the left side. In half of the animals in each group the left PF was removed immediately prior to the spontaneous firing rates recordings. In the acoustic trauma groups, spontaneous firing rates in the inferior colliculus were higher when the PF was removed compared to animals with an intact PF. This effect of PF removal was not observed in animals that did not receive acoustic trauma. These results suggest that the PF has a tonic inhibitory effect on hyperactivity in the inferior colliculus in animals with hearing loss, but not on normal spontaneous firing rates in normal hearing animals.
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Cortical and thalamic connectivity of the auditory anterior ectosylvian cortex of early-deaf cats: Implications for neural mechanisms of crossmodal plasticity
Publication date: Available online 24 December 2015
Source:Hearing Research
Author(s): M. Alex Meredith, H. Ruth Clemo, Sarah B. Corley, Nicole Chabot, Stephen G. Lomber
Early hearing loss leads to crossmodal plasticity in regions of the cerebrum that are dominated by acoustical processing in hearing subjects. Until recently, little has been known of the connectional basis of this phenomenon. One region whose crossmodal properties are well-established is the auditory field of the anterior ectosylvian sulcus (FAES) in the cat, where neurons are normally responsive to acoustic stimulation and its deactivation leads to the behavioral loss of accurate orienting toward auditory stimuli. However, in early-deaf cats, visual responsiveness predominates in the FAES and its deactivation blocks accurate orienting behavior toward visual stimuli. For such crossmodal reorganization to occur, it has been presumed that novel inputs or increased projections from non-auditory cortical areas must be generated, or that existing non-auditory connections were ‘unmasked.’ These possibilities were tested using tracer injections into the FAES of adult cats deafened early in life (and hearing controls), followed by light microscopy to localize retrogradely labeled neurons. Surprisingly, the distribution of cortical and thalamic afferents to the FAES was very similar among early-deaf and hearing animals. No new visual projection sources were identified and visual cortical connections to the FAES were comparable in projection proportions. These results support an alternate theory for the connectional basis for cross-modal plasticity that involves enhanced local branching of existing projection terminals that originate in non-auditory as well as auditory cortices.
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via IFTTT
Source:Hearing Research
Author(s): M. Alex Meredith, H. Ruth Clemo, Sarah B. Corley, Nicole Chabot, Stephen G. Lomber
Early hearing loss leads to crossmodal plasticity in regions of the cerebrum that are dominated by acoustical processing in hearing subjects. Until recently, little has been known of the connectional basis of this phenomenon. One region whose crossmodal properties are well-established is the auditory field of the anterior ectosylvian sulcus (FAES) in the cat, where neurons are normally responsive to acoustic stimulation and its deactivation leads to the behavioral loss of accurate orienting toward auditory stimuli. However, in early-deaf cats, visual responsiveness predominates in the FAES and its deactivation blocks accurate orienting behavior toward visual stimuli. For such crossmodal reorganization to occur, it has been presumed that novel inputs or increased projections from non-auditory cortical areas must be generated, or that existing non-auditory connections were ‘unmasked.’ These possibilities were tested using tracer injections into the FAES of adult cats deafened early in life (and hearing controls), followed by light microscopy to localize retrogradely labeled neurons. Surprisingly, the distribution of cortical and thalamic afferents to the FAES was very similar among early-deaf and hearing animals. No new visual projection sources were identified and visual cortical connections to the FAES were comparable in projection proportions. These results support an alternate theory for the connectional basis for cross-modal plasticity that involves enhanced local branching of existing projection terminals that originate in non-auditory as well as auditory cortices.
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Ambulation speed and corresponding mechanics are associated with changes in serum cartilage oligomeric matrix protein
Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): W. Matt Denning, Michael Becker Pardo, Jason G. Winward, Iain Hunter, Sarah Ridge, J. Ty Hopkins, C. Shane Reese, Allen C. Parcell, Matthew K. Seeley
Because serum cartilage oligomeric matrix protein (COMP) has been used to reflect articular cartilage condition, we aimed to identify walking and running mechanics that are associated with changes in serum COMP. Eighteen subjects (9 male, 9 female; age=23±2 yrs.; mass=68.3±9.6kg; height=1.70±0.08m) completed 4000 steps on an instrumented treadmill on three separate days. Each day corresponded to a different ambulation speed: slow (preferred walking speed), medium (+50% of slow), and fast (+100% of slow). Synchronized ground reaction force and video data were collected to evaluate walking mechanics. Blood samples were collected pre-, post-, 30-minute post-, and 60-minute post-ambulation to determine serum COMP concentration at these times. Serum COMP increased 29%, 18%, and 5% immediately post ambulation for the fast, medium, and slow sessions (p<0.01). When the speeds were pooled, peak ankle inversion, knee extension, knee abduction, hip flexion, hip extension, and hip abduction moment, and knee flexion angle at impact explained 61.4% of total variance in COMP concentration change (p<0.001). These results indicate that (1) certain joint mechanics are associated with acute change in serum COMP due to ambulation, and (2) increased ambulation speed increases serum COMP concentration.
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Source:Gait & Posture, Volume 44
Author(s): W. Matt Denning, Michael Becker Pardo, Jason G. Winward, Iain Hunter, Sarah Ridge, J. Ty Hopkins, C. Shane Reese, Allen C. Parcell, Matthew K. Seeley
Because serum cartilage oligomeric matrix protein (COMP) has been used to reflect articular cartilage condition, we aimed to identify walking and running mechanics that are associated with changes in serum COMP. Eighteen subjects (9 male, 9 female; age=23±2 yrs.; mass=68.3±9.6kg; height=1.70±0.08m) completed 4000 steps on an instrumented treadmill on three separate days. Each day corresponded to a different ambulation speed: slow (preferred walking speed), medium (+50% of slow), and fast (+100% of slow). Synchronized ground reaction force and video data were collected to evaluate walking mechanics. Blood samples were collected pre-, post-, 30-minute post-, and 60-minute post-ambulation to determine serum COMP concentration at these times. Serum COMP increased 29%, 18%, and 5% immediately post ambulation for the fast, medium, and slow sessions (p<0.01). When the speeds were pooled, peak ankle inversion, knee extension, knee abduction, hip flexion, hip extension, and hip abduction moment, and knee flexion angle at impact explained 61.4% of total variance in COMP concentration change (p<0.001). These results indicate that (1) certain joint mechanics are associated with acute change in serum COMP due to ambulation, and (2) increased ambulation speed increases serum COMP concentration.
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