Precedence based speech segregation in bilateral cochlear implant users

The precedence effect (PE) enables the perceptual dominance by a source (lead) over an echo (lag) in reverberant environments. In addition to facilitating sound localization, the PE can play an important role in spatial unmasking of speech. Listeners attending to binaural vocoder simulations with identical channel center frequencies and phase demonstrated PE-based benefits in a closed-set speech segregation task. When presented with the same stimuli, bilateral cochlear implant users did not derive such benefits. These findings suggest that envelope extraction in itself may not lead to a breakdown of the PE benefits, and that other factors may play a role.

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Empirical prediction of peak pressure levels in anthropogenic impulsive noise. Part I: Airgun arrays signals

This paper presents an empirical linear equation to predict peak pressure level of anthropogenic impulsive signals based on its correlation with the sound exposure level. The regression coefficients are shown to be weakly dependent on the environmental characteristics but governed by the source type and parameters. The equation can be applied to values of the sound exposure level predicted with a numerical model, which provides a significant improvement in the prediction of the peak pressure level. Part I presents the analysis for airgun arrays signals, and Part II considers the application of the empirical equation to offshore impact piling noise.

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Watermarking of linear frequency modulated pulses using chirplet graphs and stretch processing

In many underwater acoustics problems such as search and rescue, it is desirable to establish the source of the sonar pings. In this paper a methodology is proposed to watermark sonar pulses prior to transmission by embedding them with a chain of low power chirplets represented by a graph. Watermark detection is formulated using stretch processing where chirplet energies are focused on a single beat frequency only if the graph is traversed along the same path used at the source. The algorithm is tested by simulation in shallow water at varying ranges.

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Formulation of total complex power and energy flows into a discrete system

By considering total inputs into a discrete system, this letter analytically formulates and summarizes the relationships in the complex-form power and energy flows and the dissipated power and Lagrangian energy of the system. The matrix inverse method to obtain the force/moment necessary for the power/energy flow is shown as an indirect yet analytically exact method. A 2 degree-of-freedom system is employed to analytically validate the derived formulas, followed by a computational confirmation. A finite element plate-beam model is further utilized to computationally confirm the relationships in the complex power and energy flows.

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Precedence based speech segregation in bilateral cochlear implant users

The precedence effect (PE) enables the perceptual dominance by a source (lead) over an echo (lag) in reverberant environments. In addition to facilitating sound localization, the PE can play an important role in spatial unmasking of speech. Listeners attending to binaural vocoder simulations with identical channel center frequencies and phase demonstrated PE-based benefits in a closed-set speech segregation task. When presented with the same stimuli, bilateral cochlear implant users did not derive such benefits. These findings suggest that envelope extraction in itself may not lead to a breakdown of the PE benefits, and that other factors may play a role.

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Empirical prediction of peak pressure levels in anthropogenic impulsive noise. Part I: Airgun arrays signals

This paper presents an empirical linear equation to predict peak pressure level of anthropogenic impulsive signals based on its correlation with the sound exposure level. The regression coefficients are shown to be weakly dependent on the environmental characteristics but governed by the source type and parameters. The equation can be applied to values of the sound exposure level predicted with a numerical model, which provides a significant improvement in the prediction of the peak pressure level. Part I presents the analysis for airgun arrays signals, and Part II considers the application of the empirical equation to offshore impact piling noise.

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Watermarking of linear frequency modulated pulses using chirplet graphs and stretch processing

In many underwater acoustics problems such as search and rescue, it is desirable to establish the source of the sonar pings. In this paper a methodology is proposed to watermark sonar pulses prior to transmission by embedding them with a chain of low power chirplets represented by a graph. Watermark detection is formulated using stretch processing where chirplet energies are focused on a single beat frequency only if the graph is traversed along the same path used at the source. The algorithm is tested by simulation in shallow water at varying ranges.

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Formulation of total complex power and energy flows into a discrete system

By considering total inputs into a discrete system, this letter analytically formulates and summarizes the relationships in the complex-form power and energy flows and the dissipated power and Lagrangian energy of the system. The matrix inverse method to obtain the force/moment necessary for the power/energy flow is shown as an indirect yet analytically exact method. A 2 degree-of-freedom system is employed to analytically validate the derived formulas, followed by a computational confirmation. A finite element plate-beam model is further utilized to computationally confirm the relationships in the complex power and energy flows.

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Age-related changes in postural sway in preschoolers

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Evi Verbecque, Paula Hentschel Lobo da Costa, Pieter Meyns, Kaat Desloovere, Luc Vereeck, Ann Hallemans
ObjectivesThe present study aimed to investigate age-related differences of postural sway in 3- to 6-year-old typically developing children in different sensory conditions and subsequently to provide reference values for global descriptive sway parameters in preschoolers.MethodsNinety-six typically developing children, between 3 and 5 years of age, participated in this cross-sectional study. Postural sway was measured for 40s in four conditions (eyes open/eyes closed on stable ground/foam) by using a force plate. Global descriptive sway parameters were calculated and analysed using a 2×2×3 (surface×vision×age group) MANOVA (p<0.05) in the children that were able to complete the task (40s).ResultsWhen sensory information was altered, a significantly smaller number of 3- and 4-year-olds was able to complete the task. Significant main effects of vision (p<0.05), surface (p<0.001) and an interaction effect between vision and surface (p<0.05) on all postural sway parameters were found. A significant main effect of age was found for antero-posterior amplitude (p=0.047), medio-lateral root mean square (p=0.012) and area (p=0.009) between 3- and 5-year-olds and 4- and 5-year-olds. No interaction effects (surface×vision×age group) were found.ConclusionsDuring natural stance, the amount of postural sway distinguishes 5-year-olds from 3- and 4-year-olds, highlighting the need for age-specific reference values for specific balance-related sway parameters (e.g. RMS_ml). Regarding test conditions with altered sensory input, a larger number of 5-year-old children are able to perform more difficult tasks. Nevertheless, if 3- or 4-year-olds are able to perform the more difficult tasks, their performance can be compared to the older children.



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Balance recovery reactions in individuals with recurrent nonspecific low back pain: Effect of attention

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Yasaman Etemadi, Mahyar Salavati, Amir M. Arab, Tabassom Ghanavati
People who suffer from Low Back Pain (LBP) demonstrate impaired postural control. Deficits in sensory-motor systems have been proposed to be related to these changes. Considering higher cognitive process contribution to postural control, the aim of this study was to investigate the effects of cognitive load on balance control of patients with LBP. Twenty subjects with recurrent non-specific LBP and 20 healthy controls participated. They stood on a moveable platform with each foot placed on a separate force plate. They were asked to maintain their balance (a) while expecting translations of the support surface at two sizes of perturbation (b) with and without performing a cognitive (auditory Stroop) task. The outcomes included reaction time (RT), latency, initial velocity and amplitude of center of pressure response for balance, and RT for cognitive performance. Compared to the healthy group, LBP group demonstrated delayed RT and latency, and reduced initial velocity (P<0.05). Moreover, they had slower Stroop RT (F=70.88, P<0.001). Concurrent performance of tasks resulted in increased Stroop RT (F=3.42, P=0.03) and adaptation in initial velocity (F=6.70, P=0.01). At the smaller size of perturbation, cognitive load increased velocity in LBP group but decreased this variable in the healthy group. When the cognitive load was added at the larger size of perturbation, velocity of response decreased in LBP group (P<0.05). These findings imply altered cognitive regulation of dynamic balance in patients with LBP and suggest that the adopted strategy might alter depending upon the characteristics of the postural challenge.



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Reflex ankle stiffness is inversely correlated with natural body sway

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Brianna L. Julien, Andrew P. Bendrups
We aimed to determine whether effective ankle stiffness (EAS), measured during slow unperceived perturbations of stance, is related to natural anterior–posterior body sway. Because the perturbations are not perceived, any neural component of the response to perturbation is assumed to be “reflex”, in the broad sense of an involuntary response to a stimulus. Subjects stood on a force platform for three 10-min trials. EAS was obtained from the average slope (Δτ/Δα) of the relation between ankle torque (τ) and ankle angle (α), recorded during repeated perturbations delivered at the waist by a weak spring. EAS was normalised using the subject's “load stiffness” (LS), calculated from mass (m) and height (h) above the ankle joint (m·g·h). Sway was obtained from fluctuations in ankle angle prior to perturbation. Variation in EAS and sway between subjects provided spread of data for correlation. There were no significant changes in EAS or sway across trials. All subjects had higher EAS than LS and mean EAS (1124Nm/rad) was significantly greater (p<0.01) than mean LS (531Nm/rad). There was a strong significant inverse correlation between mean sway and mean normalised EAS (r=−0.68, p=0.03). We conclude that the body, in response to slow unperceived perturbations, simulates an inverted pendulum with a stiffness of about twice LS and that EAS is largely generated by neural modulation of postural muscles. The inverse correlation between EAS and body sway suggests that the reflex mechanisms responding to perturbation also influence the extent of natural sway.



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Age-related changes in postural sway in preschoolers

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Evi Verbecque, Paula Hentschel Lobo da Costa, Pieter Meyns, Kaat Desloovere, Luc Vereeck, Ann Hallemans
ObjectivesThe present study aimed to investigate age-related differences of postural sway in 3- to 6-year-old typically developing children in different sensory conditions and subsequently to provide reference values for global descriptive sway parameters in preschoolers.MethodsNinety-six typically developing children, between 3 and 5 years of age, participated in this cross-sectional study. Postural sway was measured for 40s in four conditions (eyes open/eyes closed on stable ground/foam) by using a force plate. Global descriptive sway parameters were calculated and analysed using a 2×2×3 (surface×vision×age group) MANOVA (p<0.05) in the children that were able to complete the task (40s).ResultsWhen sensory information was altered, a significantly smaller number of 3- and 4-year-olds was able to complete the task. Significant main effects of vision (p<0.05), surface (p<0.001) and an interaction effect between vision and surface (p<0.05) on all postural sway parameters were found. A significant main effect of age was found for antero-posterior amplitude (p=0.047), medio-lateral root mean square (p=0.012) and area (p=0.009) between 3- and 5-year-olds and 4- and 5-year-olds. No interaction effects (surface×vision×age group) were found.ConclusionsDuring natural stance, the amount of postural sway distinguishes 5-year-olds from 3- and 4-year-olds, highlighting the need for age-specific reference values for specific balance-related sway parameters (e.g. RMS_ml). Regarding test conditions with altered sensory input, a larger number of 5-year-old children are able to perform more difficult tasks. Nevertheless, if 3- or 4-year-olds are able to perform the more difficult tasks, their performance can be compared to the older children.



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Balance recovery reactions in individuals with recurrent nonspecific low back pain: Effect of attention

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Yasaman Etemadi, Mahyar Salavati, Amir M. Arab, Tabassom Ghanavati
People who suffer from Low Back Pain (LBP) demonstrate impaired postural control. Deficits in sensory-motor systems have been proposed to be related to these changes. Considering higher cognitive process contribution to postural control, the aim of this study was to investigate the effects of cognitive load on balance control of patients with LBP. Twenty subjects with recurrent non-specific LBP and 20 healthy controls participated. They stood on a moveable platform with each foot placed on a separate force plate. They were asked to maintain their balance (a) while expecting translations of the support surface at two sizes of perturbation (b) with and without performing a cognitive (auditory Stroop) task. The outcomes included reaction time (RT), latency, initial velocity and amplitude of center of pressure response for balance, and RT for cognitive performance. Compared to the healthy group, LBP group demonstrated delayed RT and latency, and reduced initial velocity (P<0.05). Moreover, they had slower Stroop RT (F=70.88, P<0.001). Concurrent performance of tasks resulted in increased Stroop RT (F=3.42, P=0.03) and adaptation in initial velocity (F=6.70, P=0.01). At the smaller size of perturbation, cognitive load increased velocity in LBP group but decreased this variable in the healthy group. When the cognitive load was added at the larger size of perturbation, velocity of response decreased in LBP group (P<0.05). These findings imply altered cognitive regulation of dynamic balance in patients with LBP and suggest that the adopted strategy might alter depending upon the characteristics of the postural challenge.



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via IFTTT

Reflex ankle stiffness is inversely correlated with natural body sway

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Brianna L. Julien, Andrew P. Bendrups
We aimed to determine whether effective ankle stiffness (EAS), measured during slow unperceived perturbations of stance, is related to natural anterior–posterior body sway. Because the perturbations are not perceived, any neural component of the response to perturbation is assumed to be “reflex”, in the broad sense of an involuntary response to a stimulus. Subjects stood on a force platform for three 10-min trials. EAS was obtained from the average slope (Δτ/Δα) of the relation between ankle torque (τ) and ankle angle (α), recorded during repeated perturbations delivered at the waist by a weak spring. EAS was normalised using the subject's “load stiffness” (LS), calculated from mass (m) and height (h) above the ankle joint (m·g·h). Sway was obtained from fluctuations in ankle angle prior to perturbation. Variation in EAS and sway between subjects provided spread of data for correlation. There were no significant changes in EAS or sway across trials. All subjects had higher EAS than LS and mean EAS (1124Nm/rad) was significantly greater (p<0.01) than mean LS (531Nm/rad). There was a strong significant inverse correlation between mean sway and mean normalised EAS (r=−0.68, p=0.03). We conclude that the body, in response to slow unperceived perturbations, simulates an inverted pendulum with a stiffness of about twice LS and that EAS is largely generated by neural modulation of postural muscles. The inverse correlation between EAS and body sway suggests that the reflex mechanisms responding to perturbation also influence the extent of natural sway.



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via IFTTT

Age-related changes in postural sway in preschoolers

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Evi Verbecque, Paula Hentschel Lobo da Costa, Pieter Meyns, Kaat Desloovere, Luc Vereeck, Ann Hallemans
ObjectivesThe present study aimed to investigate age-related differences of postural sway in 3- to 6-year-old typically developing children in different sensory conditions and subsequently to provide reference values for global descriptive sway parameters in preschoolers.MethodsNinety-six typically developing children, between 3 and 5 years of age, participated in this cross-sectional study. Postural sway was measured for 40s in four conditions (eyes open/eyes closed on stable ground/foam) by using a force plate. Global descriptive sway parameters were calculated and analysed using a 2×2×3 (surface×vision×age group) MANOVA (p<0.05) in the children that were able to complete the task (40s).ResultsWhen sensory information was altered, a significantly smaller number of 3- and 4-year-olds was able to complete the task. Significant main effects of vision (p<0.05), surface (p<0.001) and an interaction effect between vision and surface (p<0.05) on all postural sway parameters were found. A significant main effect of age was found for antero-posterior amplitude (p=0.047), medio-lateral root mean square (p=0.012) and area (p=0.009) between 3- and 5-year-olds and 4- and 5-year-olds. No interaction effects (surface×vision×age group) were found.ConclusionsDuring natural stance, the amount of postural sway distinguishes 5-year-olds from 3- and 4-year-olds, highlighting the need for age-specific reference values for specific balance-related sway parameters (e.g. RMS_ml). Regarding test conditions with altered sensory input, a larger number of 5-year-old children are able to perform more difficult tasks. Nevertheless, if 3- or 4-year-olds are able to perform the more difficult tasks, their performance can be compared to the older children.



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Balance recovery reactions in individuals with recurrent nonspecific low back pain: Effect of attention

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Yasaman Etemadi, Mahyar Salavati, Amir M. Arab, Tabassom Ghanavati
People who suffer from Low Back Pain (LBP) demonstrate impaired postural control. Deficits in sensory-motor systems have been proposed to be related to these changes. Considering higher cognitive process contribution to postural control, the aim of this study was to investigate the effects of cognitive load on balance control of patients with LBP. Twenty subjects with recurrent non-specific LBP and 20 healthy controls participated. They stood on a moveable platform with each foot placed on a separate force plate. They were asked to maintain their balance (a) while expecting translations of the support surface at two sizes of perturbation (b) with and without performing a cognitive (auditory Stroop) task. The outcomes included reaction time (RT), latency, initial velocity and amplitude of center of pressure response for balance, and RT for cognitive performance. Compared to the healthy group, LBP group demonstrated delayed RT and latency, and reduced initial velocity (P<0.05). Moreover, they had slower Stroop RT (F=70.88, P<0.001). Concurrent performance of tasks resulted in increased Stroop RT (F=3.42, P=0.03) and adaptation in initial velocity (F=6.70, P=0.01). At the smaller size of perturbation, cognitive load increased velocity in LBP group but decreased this variable in the healthy group. When the cognitive load was added at the larger size of perturbation, velocity of response decreased in LBP group (P<0.05). These findings imply altered cognitive regulation of dynamic balance in patients with LBP and suggest that the adopted strategy might alter depending upon the characteristics of the postural challenge.



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via IFTTT

Reflex ankle stiffness is inversely correlated with natural body sway

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Brianna L. Julien, Andrew P. Bendrups
We aimed to determine whether effective ankle stiffness (EAS), measured during slow unperceived perturbations of stance, is related to natural anterior–posterior body sway. Because the perturbations are not perceived, any neural component of the response to perturbation is assumed to be “reflex”, in the broad sense of an involuntary response to a stimulus. Subjects stood on a force platform for three 10-min trials. EAS was obtained from the average slope (Δτ/Δα) of the relation between ankle torque (τ) and ankle angle (α), recorded during repeated perturbations delivered at the waist by a weak spring. EAS was normalised using the subject's “load stiffness” (LS), calculated from mass (m) and height (h) above the ankle joint (m·g·h). Sway was obtained from fluctuations in ankle angle prior to perturbation. Variation in EAS and sway between subjects provided spread of data for correlation. There were no significant changes in EAS or sway across trials. All subjects had higher EAS than LS and mean EAS (1124Nm/rad) was significantly greater (p<0.01) than mean LS (531Nm/rad). There was a strong significant inverse correlation between mean sway and mean normalised EAS (r=−0.68, p=0.03). We conclude that the body, in response to slow unperceived perturbations, simulates an inverted pendulum with a stiffness of about twice LS and that EAS is largely generated by neural modulation of postural muscles. The inverse correlation between EAS and body sway suggests that the reflex mechanisms responding to perturbation also influence the extent of natural sway.



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Dehydration effects of a V2 antagonist on endolymphatic hydrops in guinea pigs

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Naoya Egami, Akinobu Kakigi, Taizo Takeda, Tatsuya Yamasoba
We investigated the influence of vasopressin type 2 receptor antagonist (OPC-41061; Tolvaptan) on experimentally induced endolymphatic hydrops (EH) in guinea pigs. In the first series, the endolymphatic sac (ES) of the left ear of all animals was electrocauterized. Four weeks after surgery, the animals were allocated to four groups: three systemic applications groups (saline, OPC 10 and 100 mg/kg) and a local round window (RW) OPC 1mg/body application group. We examined the histopathology of the temporal bones and assessed volumetric changes of the endolymphatic space in the cochlea and saccule. In the second series, we investigated the effects of systemic and topical applications of OPC on plasma vasopressin (p-VP) concentrations and plasma osmolality (p-OSM). In the first series, we found that EH was reduced in the OPC 10 mg/kg systemic and OPC RW application groups. In contrast, EH increased in the OPC 100 mg/kg systemic application group. In the second series, neither p-VP levels nor p-OSM were significantly different among the non-OPC, OPC 10 mg/kg systemic, and OPC RW application groups. However, in the OPC 100 mg/kg systemic application group, the p-VP level was significantly higher than that in other groups, and p-OSM was higher than that in the non-OPC group. The systemic application of a low dose of OPC and topical application of OPC resulted in reduced EH in the face of minimal systemic effects (p-VP and p-OSM). These findings suggest that OPC-41061 may be one useful treatment option for EH.



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Somatic memory and gain increase as preconditions for tinnitus: insights from congenital deafness

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Jos J. Eggermont, Andrej Kral
Tinnitus is the conscious perception of sound heard in the absence of physical sound sources internal or external to the body. The characterization of tinnitus by its spectrum reflects the missing frequencies originally represented in the hearing loss, i.e., partially or completely deafferented, region. The tinnitus percept, despite a total hearing loss, may thus be dependent on the persisting existence of a somatic memory for the “lost” frequencies. Somatic memory in this context is the reference for phantom sensations attributed to missing sensory surfaces or parts thereof. This raises the question whether tinnitus can exist in congenital deafness, were somatic representations have not been formed. We review the development of tonotopic maps in altricial and precocial animals evidence for a lack of tinnitus in congenital deafness and the effects of cochlear implants on the formation of tonotopic maps in the congenitally deaf. The latter relates to the emergence of tinnitus in these subjects. The reviewed material is consistent with the hypothesis that tinnitus requires an established and actively used somatotopic map that leads to a corresponding somatic memory. The absence of such experience explains the absence of tinnitus in congenital bilateral and unilateral deafness.



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Dehydration effects of a V2 antagonist on endolymphatic hydrops in guinea pigs

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Naoya Egami, Akinobu Kakigi, Taizo Takeda, Tatsuya Yamasoba
We investigated the influence of vasopressin type 2 receptor antagonist (OPC-41061; Tolvaptan) on experimentally induced endolymphatic hydrops (EH) in guinea pigs. In the first series, the endolymphatic sac (ES) of the left ear of all animals was electrocauterized. Four weeks after surgery, the animals were allocated to four groups: three systemic applications groups (saline, OPC 10 and 100 mg/kg) and a local round window (RW) OPC 1mg/body application group. We examined the histopathology of the temporal bones and assessed volumetric changes of the endolymphatic space in the cochlea and saccule. In the second series, we investigated the effects of systemic and topical applications of OPC on plasma vasopressin (p-VP) concentrations and plasma osmolality (p-OSM). In the first series, we found that EH was reduced in the OPC 10 mg/kg systemic and OPC RW application groups. In contrast, EH increased in the OPC 100 mg/kg systemic application group. In the second series, neither p-VP levels nor p-OSM were significantly different among the non-OPC, OPC 10 mg/kg systemic, and OPC RW application groups. However, in the OPC 100 mg/kg systemic application group, the p-VP level was significantly higher than that in other groups, and p-OSM was higher than that in the non-OPC group. The systemic application of a low dose of OPC and topical application of OPC resulted in reduced EH in the face of minimal systemic effects (p-VP and p-OSM). These findings suggest that OPC-41061 may be one useful treatment option for EH.



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Somatic memory and gain increase as preconditions for tinnitus: insights from congenital deafness

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Jos J. Eggermont, Andrej Kral
Tinnitus is the conscious perception of sound heard in the absence of physical sound sources internal or external to the body. The characterization of tinnitus by its spectrum reflects the missing frequencies originally represented in the hearing loss, i.e., partially or completely deafferented, region. The tinnitus percept, despite a total hearing loss, may thus be dependent on the persisting existence of a somatic memory for the “lost” frequencies. Somatic memory in this context is the reference for phantom sensations attributed to missing sensory surfaces or parts thereof. This raises the question whether tinnitus can exist in congenital deafness, were somatic representations have not been formed. We review the development of tonotopic maps in altricial and precocial animals evidence for a lack of tinnitus in congenital deafness and the effects of cochlear implants on the formation of tonotopic maps in the congenitally deaf. The latter relates to the emergence of tinnitus in these subjects. The reviewed material is consistent with the hypothesis that tinnitus requires an established and actively used somatotopic map that leads to a corresponding somatic memory. The absence of such experience explains the absence of tinnitus in congenital bilateral and unilateral deafness.



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via IFTTT

Dehydration effects of a V2 antagonist on endolymphatic hydrops in guinea pigs

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Naoya Egami, Akinobu Kakigi, Taizo Takeda, Tatsuya Yamasoba
We investigated the influence of vasopressin type 2 receptor antagonist (OPC-41061; Tolvaptan) on experimentally induced endolymphatic hydrops (EH) in guinea pigs. In the first series, the endolymphatic sac (ES) of the left ear of all animals was electrocauterized. Four weeks after surgery, the animals were allocated to four groups: three systemic applications groups (saline, OPC 10 and 100 mg/kg) and a local round window (RW) OPC 1mg/body application group. We examined the histopathology of the temporal bones and assessed volumetric changes of the endolymphatic space in the cochlea and saccule. In the second series, we investigated the effects of systemic and topical applications of OPC on plasma vasopressin (p-VP) concentrations and plasma osmolality (p-OSM). In the first series, we found that EH was reduced in the OPC 10 mg/kg systemic and OPC RW application groups. In contrast, EH increased in the OPC 100 mg/kg systemic application group. In the second series, neither p-VP levels nor p-OSM were significantly different among the non-OPC, OPC 10 mg/kg systemic, and OPC RW application groups. However, in the OPC 100 mg/kg systemic application group, the p-VP level was significantly higher than that in other groups, and p-OSM was higher than that in the non-OPC group. The systemic application of a low dose of OPC and topical application of OPC resulted in reduced EH in the face of minimal systemic effects (p-VP and p-OSM). These findings suggest that OPC-41061 may be one useful treatment option for EH.



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via IFTTT

Somatic memory and gain increase as preconditions for tinnitus: insights from congenital deafness

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Jos J. Eggermont, Andrej Kral
Tinnitus is the conscious perception of sound heard in the absence of physical sound sources internal or external to the body. The characterization of tinnitus by its spectrum reflects the missing frequencies originally represented in the hearing loss, i.e., partially or completely deafferented, region. The tinnitus percept, despite a total hearing loss, may thus be dependent on the persisting existence of a somatic memory for the “lost” frequencies. Somatic memory in this context is the reference for phantom sensations attributed to missing sensory surfaces or parts thereof. This raises the question whether tinnitus can exist in congenital deafness, were somatic representations have not been formed. We review the development of tonotopic maps in altricial and precocial animals evidence for a lack of tinnitus in congenital deafness and the effects of cochlear implants on the formation of tonotopic maps in the congenitally deaf. The latter relates to the emergence of tinnitus in these subjects. The reviewed material is consistent with the hypothesis that tinnitus requires an established and actively used somatotopic map that leads to a corresponding somatic memory. The absence of such experience explains the absence of tinnitus in congenital bilateral and unilateral deafness.



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via IFTTT

Dehydration effects of a V2 antagonist on endolymphatic hydrops in guinea pigs

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Naoya Egami, Akinobu Kakigi, Taizo Takeda, Tatsuya Yamasoba
We investigated the influence of vasopressin type 2 receptor antagonist (OPC-41061; Tolvaptan) on experimentally induced endolymphatic hydrops (EH) in guinea pigs. In the first series, the endolymphatic sac (ES) of the left ear of all animals was electrocauterized. Four weeks after surgery, the animals were allocated to four groups: three systemic applications groups (saline, OPC 10 and 100 mg/kg) and a local round window (RW) OPC 1mg/body application group. We examined the histopathology of the temporal bones and assessed volumetric changes of the endolymphatic space in the cochlea and saccule. In the second series, we investigated the effects of systemic and topical applications of OPC on plasma vasopressin (p-VP) concentrations and plasma osmolality (p-OSM). In the first series, we found that EH was reduced in the OPC 10 mg/kg systemic and OPC RW application groups. In contrast, EH increased in the OPC 100 mg/kg systemic application group. In the second series, neither p-VP levels nor p-OSM were significantly different among the non-OPC, OPC 10 mg/kg systemic, and OPC RW application groups. However, in the OPC 100 mg/kg systemic application group, the p-VP level was significantly higher than that in other groups, and p-OSM was higher than that in the non-OPC group. The systemic application of a low dose of OPC and topical application of OPC resulted in reduced EH in the face of minimal systemic effects (p-VP and p-OSM). These findings suggest that OPC-41061 may be one useful treatment option for EH.



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Somatic memory and gain increase as preconditions for tinnitus: insights from congenital deafness

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Jos J. Eggermont, Andrej Kral
Tinnitus is the conscious perception of sound heard in the absence of physical sound sources internal or external to the body. The characterization of tinnitus by its spectrum reflects the missing frequencies originally represented in the hearing loss, i.e., partially or completely deafferented, region. The tinnitus percept, despite a total hearing loss, may thus be dependent on the persisting existence of a somatic memory for the “lost” frequencies. Somatic memory in this context is the reference for phantom sensations attributed to missing sensory surfaces or parts thereof. This raises the question whether tinnitus can exist in congenital deafness, were somatic representations have not been formed. We review the development of tonotopic maps in altricial and precocial animals evidence for a lack of tinnitus in congenital deafness and the effects of cochlear implants on the formation of tonotopic maps in the congenitally deaf. The latter relates to the emergence of tinnitus in these subjects. The reviewed material is consistent with the hypothesis that tinnitus requires an established and actively used somatotopic map that leads to a corresponding somatic memory. The absence of such experience explains the absence of tinnitus in congenital bilateral and unilateral deafness.



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Dehydration effects of a V2 antagonist on endolymphatic hydrops in guinea pigs

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Naoya Egami, Akinobu Kakigi, Taizo Takeda, Tatsuya Yamasoba
We investigated the influence of vasopressin type 2 receptor antagonist (OPC-41061; Tolvaptan) on experimentally induced endolymphatic hydrops (EH) in guinea pigs. In the first series, the endolymphatic sac (ES) of the left ear of all animals was electrocauterized. Four weeks after surgery, the animals were allocated to four groups: three systemic applications groups (saline, OPC 10 and 100 mg/kg) and a local round window (RW) OPC 1mg/body application group. We examined the histopathology of the temporal bones and assessed volumetric changes of the endolymphatic space in the cochlea and saccule. In the second series, we investigated the effects of systemic and topical applications of OPC on plasma vasopressin (p-VP) concentrations and plasma osmolality (p-OSM). In the first series, we found that EH was reduced in the OPC 10 mg/kg systemic and OPC RW application groups. In contrast, EH increased in the OPC 100 mg/kg systemic application group. In the second series, neither p-VP levels nor p-OSM were significantly different among the non-OPC, OPC 10 mg/kg systemic, and OPC RW application groups. However, in the OPC 100 mg/kg systemic application group, the p-VP level was significantly higher than that in other groups, and p-OSM was higher than that in the non-OPC group. The systemic application of a low dose of OPC and topical application of OPC resulted in reduced EH in the face of minimal systemic effects (p-VP and p-OSM). These findings suggest that OPC-41061 may be one useful treatment option for EH.



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Somatic memory and gain increase as preconditions for tinnitus: insights from congenital deafness

Publication date: Available online 21 December 2015
Source:Hearing Research
Author(s): Jos J. Eggermont, Andrej Kral
Tinnitus is the conscious perception of sound heard in the absence of physical sound sources internal or external to the body. The characterization of tinnitus by its spectrum reflects the missing frequencies originally represented in the hearing loss, i.e., partially or completely deafferented, region. The tinnitus percept, despite a total hearing loss, may thus be dependent on the persisting existence of a somatic memory for the “lost” frequencies. Somatic memory in this context is the reference for phantom sensations attributed to missing sensory surfaces or parts thereof. This raises the question whether tinnitus can exist in congenital deafness, were somatic representations have not been formed. We review the development of tonotopic maps in altricial and precocial animals evidence for a lack of tinnitus in congenital deafness and the effects of cochlear implants on the formation of tonotopic maps in the congenitally deaf. The latter relates to the emergence of tinnitus in these subjects. The reviewed material is consistent with the hypothesis that tinnitus requires an established and actively used somatotopic map that leads to a corresponding somatic memory. The absence of such experience explains the absence of tinnitus in congenital bilateral and unilateral deafness.



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