Ablation of the auditory cortex results in changes in the expression of neurotransmission-related mRNAs in the cochlea

Publication date: Available online 16 February 2017
Source:Hearing Research
Author(s): Verónica Lamas, José M. Juiz, Miguel A. Merchán
The auditory cortex (AC) dynamically regulates responses of the Organ of Corti to sound through descending connections to both the medial (MOC) and lateral (LOC) olivocochlear efferent systems. We have recently provided evidence that AC has a reinforcement role in the responses to sound of the auditory brainstem nuclei. In a molecular level, we have shown that descending inputs from AC are needed to regulate the expression of molecules involved in outer hair cell (OHC) electromotility control, such as prestin and the α10 nicotinic acetylcholine receptor (nAchR). In this report, we show that descending connections from AC to olivocochlear neurons are necessary to regulate the expression of molecules involved in cochlear afferent signaling. RT-qPCR was performed in rats at 1, 7 and 15 days after unilateral ablation of the AC, and analyzed the time course changes in gene transcripts involved in neurotransmission at the first auditory synapse. This included the glutamate metabolism enzyme glutamate decarboxylase 1 (glud1) and AMPA glutamate receptor subunits GluA2-4. In addition, gene transcripts involved in efferent regulation of type I spiral ganglion neuron (SGN) excitability mediated by LOC, such as the α7 nAchR, the D2 dopamine receptor, and the α1, and γ2 GABAA receptor subunits, were also investigated. Unilateral AC ablation induced up-regulation of GluA3 receptor subunit transcripts, whereas both GluA2 and GluA4 mRNA receptors were down-regulated already at 1 day after the ablation. Unilateral removal of the AC also resulted in up-regulation of the transcripts for α7 nAchR subunit, D2 dopamine receptor, and α1 GABAA receptor subunit at 1 day after the ablation. Fifteen days after the injury, AC ablations induced an up-regulation of glud1 transcripts.



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The relation between ECAP measurements and the effect of rate on behavioral thresholds in cochlear implant users

Publication date: Available online 16 February 2017
Source:Hearing Research
Author(s): Colette M. McKay, Nicholas Smale
It has been shown that electrically evoked compound action potential (ECAP) thresholds are not sufficiently predictive of behavioral thresholds to allow their use as a totally objective method to program a cochlear implant. Previous animal studies have shown that two other ECAP parameters (the ECAP amplitude growth slope and the effect on ECAPs of changing the phase duration (PD) or interphase gap (IPG)), and the way that behavioral thresholds change with increasing rate of stimulation, are associated with cochlear health. This experiment tested the hypotheses that a) the degree to which behavioral thresholds change with rate of stimulation is associated with either or both of those two ECAP parameters, and that b) the accuracy of ECAP thresholds for predicting behavioral thresholds at clinically relevant rates can be increased by including those additional ECAP parameters. Both these hypotheses were confirmed by the data. The ECAP slope was associated with within-subject variation across electrode positions of both behavioral thresholds and the change of thresholds with increasing rate. The effect of changes in IPG or PD on ECAPs was moderately associated with between-subjects variations in both average absolute behavioral thresholds and the average effect of rate on thresholds. The inclusion of the IPG/PD effect to predict average absolute behavioral thresholds for each subject and inclusion of the ECAP growth slope to predict variation in relative thresholds across electrode positions in the same subject led to a significant increase in accuracy of the predicted behavioral thresholds.



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Ablation of the auditory cortex results in changes in the expression of neurotransmission-related mRNAs in the cochlea

Publication date: Available online 16 February 2017
Source:Hearing Research
Author(s): Verónica Lamas, José M. Juiz, Miguel A. Merchán
The auditory cortex (AC) dynamically regulates responses of the Organ of Corti to sound through descending connections to both the medial (MOC) and lateral (LOC) olivocochlear efferent systems. We have recently provided evidence that AC has a reinforcement role in the responses to sound of the auditory brainstem nuclei. In a molecular level, we have shown that descending inputs from AC are needed to regulate the expression of molecules involved in outer hair cell (OHC) electromotility control, such as prestin and the α10 nicotinic acetylcholine receptor (nAchR). In this report, we show that descending connections from AC to olivocochlear neurons are necessary to regulate the expression of molecules involved in cochlear afferent signaling. RT-qPCR was performed in rats at 1, 7 and 15 days after unilateral ablation of the AC, and analyzed the time course changes in gene transcripts involved in neurotransmission at the first auditory synapse. This included the glutamate metabolism enzyme glutamate decarboxylase 1 (glud1) and AMPA glutamate receptor subunits GluA2-4. In addition, gene transcripts involved in efferent regulation of type I spiral ganglion neuron (SGN) excitability mediated by LOC, such as the α7 nAchR, the D2 dopamine receptor, and the α1, and γ2 GABAA receptor subunits, were also investigated. Unilateral AC ablation induced up-regulation of GluA3 receptor subunit transcripts, whereas both GluA2 and GluA4 mRNA receptors were down-regulated already at 1 day after the ablation. Unilateral removal of the AC also resulted in up-regulation of the transcripts for α7 nAchR subunit, D2 dopamine receptor, and α1 GABAA receptor subunit at 1 day after the ablation. Fifteen days after the injury, AC ablations induced an up-regulation of glud1 transcripts.



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The relation between ECAP measurements and the effect of rate on behavioral thresholds in cochlear implant users

Publication date: Available online 16 February 2017
Source:Hearing Research
Author(s): Colette M. McKay, Nicholas Smale
It has been shown that electrically evoked compound action potential (ECAP) thresholds are not sufficiently predictive of behavioral thresholds to allow their use as a totally objective method to program a cochlear implant. Previous animal studies have shown that two other ECAP parameters (the ECAP amplitude growth slope and the effect on ECAPs of changing the phase duration (PD) or interphase gap (IPG)), and the way that behavioral thresholds change with increasing rate of stimulation, are associated with cochlear health. This experiment tested the hypotheses that a) the degree to which behavioral thresholds change with rate of stimulation is associated with either or both of those two ECAP parameters, and that b) the accuracy of ECAP thresholds for predicting behavioral thresholds at clinically relevant rates can be increased by including those additional ECAP parameters. Both these hypotheses were confirmed by the data. The ECAP slope was associated with within-subject variation across electrode positions of both behavioral thresholds and the change of thresholds with increasing rate. The effect of changes in IPG or PD on ECAPs was moderately associated with between-subjects variations in both average absolute behavioral thresholds and the average effect of rate on thresholds. The inclusion of the IPG/PD effect to predict average absolute behavioral thresholds for each subject and inclusion of the ECAP growth slope to predict variation in relative thresholds across electrode positions in the same subject led to a significant increase in accuracy of the predicted behavioral thresholds.



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Ablation of the auditory cortex results in changes in the expression of neurotransmission-related mRNAs in the cochlea

Publication date: Available online 16 February 2017
Source:Hearing Research
Author(s): Verónica Lamas, José M. Juiz, Miguel A. Merchán
The auditory cortex (AC) dynamically regulates responses of the Organ of Corti to sound through descending connections to both the medial (MOC) and lateral (LOC) olivocochlear efferent systems. We have recently provided evidence that AC has a reinforcement role in the responses to sound of the auditory brainstem nuclei. In a molecular level, we have shown that descending inputs from AC are needed to regulate the expression of molecules involved in outer hair cell (OHC) electromotility control, such as prestin and the α10 nicotinic acetylcholine receptor (nAchR). In this report, we show that descending connections from AC to olivocochlear neurons are necessary to regulate the expression of molecules involved in cochlear afferent signaling. RT-qPCR was performed in rats at 1, 7 and 15 days after unilateral ablation of the AC, and analyzed the time course changes in gene transcripts involved in neurotransmission at the first auditory synapse. This included the glutamate metabolism enzyme glutamate decarboxylase 1 (glud1) and AMPA glutamate receptor subunits GluA2-4. In addition, gene transcripts involved in efferent regulation of type I spiral ganglion neuron (SGN) excitability mediated by LOC, such as the α7 nAchR, the D2 dopamine receptor, and the α1, and γ2 GABAA receptor subunits, were also investigated. Unilateral AC ablation induced up-regulation of GluA3 receptor subunit transcripts, whereas both GluA2 and GluA4 mRNA receptors were down-regulated already at 1 day after the ablation. Unilateral removal of the AC also resulted in up-regulation of the transcripts for α7 nAchR subunit, D2 dopamine receptor, and α1 GABAA receptor subunit at 1 day after the ablation. Fifteen days after the injury, AC ablations induced an up-regulation of glud1 transcripts.



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The relation between ECAP measurements and the effect of rate on behavioral thresholds in cochlear implant users

Publication date: Available online 16 February 2017
Source:Hearing Research
Author(s): Colette M. McKay, Nicholas Smale
It has been shown that electrically evoked compound action potential (ECAP) thresholds are not sufficiently predictive of behavioral thresholds to allow their use as a totally objective method to program a cochlear implant. Previous animal studies have shown that two other ECAP parameters (the ECAP amplitude growth slope and the effect on ECAPs of changing the phase duration (PD) or interphase gap (IPG)), and the way that behavioral thresholds change with increasing rate of stimulation, are associated with cochlear health. This experiment tested the hypotheses that a) the degree to which behavioral thresholds change with rate of stimulation is associated with either or both of those two ECAP parameters, and that b) the accuracy of ECAP thresholds for predicting behavioral thresholds at clinically relevant rates can be increased by including those additional ECAP parameters. Both these hypotheses were confirmed by the data. The ECAP slope was associated with within-subject variation across electrode positions of both behavioral thresholds and the change of thresholds with increasing rate. The effect of changes in IPG or PD on ECAPs was moderately associated with between-subjects variations in both average absolute behavioral thresholds and the average effect of rate on thresholds. The inclusion of the IPG/PD effect to predict average absolute behavioral thresholds for each subject and inclusion of the ECAP growth slope to predict variation in relative thresholds across electrode positions in the same subject led to a significant increase in accuracy of the predicted behavioral thresholds.



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Tinnitus Cure 2017

 

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Tinnitus Cure 2017

For people trying to find a tinnitus cure 2017 may be the greatest year ever. There is more hope for an effective treatment for ever before. The difficult questions of tinnitus diagnosis and amelioration have been substantially answered in recent years. The precise vector of the syndrome, which is the derangement or degradation of the microscopic structures of the ear, cannot be directly treated at this time. However, great strides have been made in precise detection and diagnosis, and that means more effective palliative efforts than ever before.

For example, careful training and testing with a series of lab rats has provided some of the deepest insights yet into the tinnitus condition and the ways in which those who have it live with it. The anatomical structure of the ear is quite similar in both rats and human beings, and a tremendous amount of information can be gleaned from animal testing. The problem is that tinnitus is a subjective condition, presenting no trauma on the surface, so there have been great difficulties in measuring and quantifying the condition among animals. Precise post-Pavlovian methods of training and conditioning have yielded a population of rats that can be objectively tested for the presence of tinnitus. One of the most interesting things about the study is that they have proven the syndrome can be intermittent. There are days of the week when it might be worse than others, and there can also be wide variance from hour to hour. Certain types of physical conditions appear to trigger it, while others seem to ameliorate it.

There is also hope for a tinnitus cure 2017 from an unexpected quarter. Chinese medical practices have reported broad success in treatment of tinnitus, though the precise mechanism by which this is accomplished is not yet known. A team of researchers in Germany has carefully evaluated Chinese-based treatments on tinnitus and found them to be consistently efficacious. A placebo hypothesis probably cannot completely explain the relief experienced by patients using these methods, but there is an interesting possibility of progress that comes from the synthesis of Chinese and western medical traditions. Now that western science has found a reproducible way to measure tinnitus in certain animals, perhaps the placebo effect can finally be ruled out. That means that Chinese-based treatments can be developed that will work on these subjects, and the progress will be measurable by the western tradition. They can treat the experimental animals through this unexplored new tradition, identify which parts of the medical process are the most efficacious, expand their knowledge of the condition and work towards a partial or complete cure.

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Neurological outcome of patients with cryopyrin-associated periodic syndrome (CAPS).

Neurological outcome of patients with cryopyrin-associated periodic syndrome (CAPS).

Orphanet J Rare Dis. 2017 Feb 14;12(1):33

Authors: Mamoudjy N, Maurey H, Marie I, Koné-Paut I, Deiva K

Abstract
BACKGROUND: To assess the neurological involvement and outcome, including school and professional performances, of adults and children with cryopyrin-associated periodic syndrome (CAPS).
METHODS: In this observational study, patients with genetically proven CAPS and followed in the national referral centre for autoinflammatory diseases at Bicêtre hospital were assessed. Neurological manifestations, CSF data and MRI results at diagnosis and during follow-up were analyzed.
RESULTS: Twenty-four patients (15 adults and 9 children at diagnosis) with CAPS were included. The median age at disease onset was 0 year (birth) [range 0-14], the median age at diagnosis was 20 years [range 0-53] and the mean duration of follow-up was 10.4 ± 2 years. Neurological involvement at diagnosis, mostly headaches and hearing loss, was noted in 17 patients (71%). Two patients of the same family had abnormal brain MRI. A439V mutation is frequently associated with a non-neurological phenotype while R260W mutation tends to be associated with neurological involvement. Eleven adult patients (61%) and 3 children (50%) underwent school difficulties.
CONCLUSION: Neurological involvement is frequent in patients with CAPS and the majority of patients presented difficulties in school performances with consequences in the professional outcome during adulthood. Further studies in larger cohorts of children with CAPS focusing in intellectual efficiency and school performances are necessary.

PMID: 28196516 [PubMed - in process]

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Effect of age-related hearing loss on the click-rate-induced facilitation of acoustic reflex thresholds

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Effect of age-related hearing loss on the click-rate-induced facilitation of acoustic reflex thresholds

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Effect of age-related hearing loss on the click-rate-induced facilitation of acoustic reflex thresholds

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