Engraftment of Human Stem Cell-Derived Otic Progenitors in the Damaged Cochlea.

Most cases of sensorineural deafness are caused by degeneration of hair cells. Although stem/progenitor cell therapy is becoming a promising treatment strategy in a variety of organ systems, cell engraftment in the adult mammalian cochlea has not yet been demonstrated. In this study, we generated human otic progenitor cells (hOPCs) from induced pluripotent stem cells (iPSCs) in vitro and identified these cells by the expression of known otic markers.

Adjustment of the dynamic weight distribution as a sensitive parameter for diagnosis of postural alteration in a rodent model of vestibular deficit.

Vestibular disorders, by inducing significant posturo-locomotor and cognitive disorders, can significantly impair the most basic tasks of everyday life. Their precise diagnosis is essential to implement appropriate therapeutic countermeasures. Monitoring their evolution is also very important to validate or, on the contrary, to adapt the undertaken therapeutic actions.

Forward Masking in Cochlear Implant Users: Electrophysiological and Psychophysical Data Using Pulse Train Maskers.

Electrical stimulation of auditory nerve fibers using cochlear implants (CI) shows psychophysical forward masking (pFM) up to several hundreds of milliseconds. By contrast, recovery of electrically evoked compound action potentials (eCAPs) from forward masking (eFM) was shown to be more rapid, with time constants no greater than a few milliseconds. These discrepancies suggested two main contributors to pFM: a rapid-recovery process due to refractory properties of the auditory nerve and a slow-recovery process arising from more central structures.

Effects of Pulse Shape and Polarity on Sensitivity to Cochlear Implant Stimulation: A Chronic Study in Guinea Pigs.

Most cochlear implants (CIs) stimulate the auditory nerve with trains of symmetric biphasic pulses consisting of two phases of opposite polarity. Animal and human studies have shown that both polarities can elicit neural responses. In human CI listeners, studies have shown that at suprathreshold levels, the anodic phase is more effective than the cathodic phase.

Erratum to: Effects of Pulse Shape and Polarity on Sensitivity to Cochlear Implant Stimulation: A Chronic Study in Guinea Pigs.

In the original version of the chapter, the labels on the x-axis of Figure 2, panels A and B were wrong. This incorrect figure has been replaced with the below figure.

KCNK5 channels mostly expressed in cochlear outer sulcus cells are indispensable for hearing.

In the cochlea, K(+) is essential for mechano-electrical transduction. Here, we explore cochlear structure and function in mice lacking K(+) channels of the two-pore domain family. A profound deafness associated with a decrease in endocochlear potential is found in adult Kcnk5(-/-) mice.

Long-term tinnitus suppression with linear octave frequency transposition hearing AIDS.

Over the last three years of hearing aid dispensing, it was observed that among 74 subjects fitted with a linear octave frequency transposition (LOFT) hearing aid, 60 reported partial or complete tinnitus suppression during day and night, an effect still lasting after several months or years of daily use. We report in more details on 38 subjects from whom we obtained quantified measures of tinnitus suppression through visual analog scaling and several additional psychoacoustic and audiometric measures. The long-term suppression seems independent of subject age, and of duration and subjective localization of tinnitus.

Temporal-envelope reconstruction for hearing-impaired listeners.

Recent studies suggest that normal-hearing listeners maintain robust speech intelligibility despite severe degradations of amplitude-modulation (AM) cues, by using temporal-envelope information recovered from broadband frequency-modulation (FM) speech cues at the output of cochlear filters. This study aimed to assess whether cochlear damage affects this capacity to reconstruct temporal-envelope information from FM. This was achieved by measuring the ability of 40 normal-hearing listeners and 41 listeners with mild-to-moderate hearing loss to identify syllables processed to degrade AM cues while leaving FM cues intact within three broad frequency bands spanning the range 65-3,645 Hz.

Age-related impairment of ultrasonic vocalization in Tau.P301L mice: possible implication for progressive language disorders.

Background: Tauopathies, including Alzheimer's Disease, are the most frequent neurodegenerative diseases in elderly people and cause various cognitive, behavioural and motor defects, but also progressive language disorders. For communication and social interactions, mice produce ultrasonic vocalization (USV) via expiratory airflow through the larynx. We examined USV of Tau.

Neural changes in the auditory cortex of awake guinea pigs after two tinnitus inducers: salicylate and acoustic trauma.

Tinnitus, also called phantom auditory perception, is a major health problem in western countries. As such, a significant amount of effort has been devoted to understanding its mechanisms, including studies in animals wherein a supposed "tinnitus state" can be induced. Here, we studied on the same awake animals the effects of a high-dose of salicylate and of an acoustic trauma both at levels known to induce tinnitus.

Ensemble spontaneous activity alterations detected by CISA approach.

In this paper, we propose a method for detecting alterations in the Ensemble Spontaneous Activity (ESA), a random signal representing the composite spontaneous contribution of the auditory nerve recorded on the round window. The proposed method is based on shape analysis of the ESA amplitude histogram. For this task, we use a recent approach, the Corrected Integral Shape Averaging (CISA).

Experimental estrogen-induced hyperprolactinemia results in bone-related hearing loss in the guinea pig.

Our group (Horner KC, Guieu R, Magnan J, Chays A, Cazals Y. Neuropsychopharmacology 26: 135-138, 2002) has earlier described hyperprolactinemia in some patients presenting inner ear dysfunction. However, in that study, it was not possible to determine whether hyperprolactinemia was a cause or an effect of the symptoms.

Loudness reduction induced by a contralateral tone.

The induced reduction in the loudness (ILR) of a weaker tone caused by a preceding stronger tone was measured with both tones in the same ear (ipsilateral ILR) and also in opposite ears (contralateral ILR). The two tones were always equal in duration and were presented repeatedly over several minutes. When the tone duration was 200 ms, for 24 listeners the loudness reduction averaged 11 dB under ipsilateral ILR and 6 dB under contralateral ILR.

Hyperbaric oxygenation with corticoid in experimental acoustic trauma.

Among possible therapies after acute acoustic trauma, hyperbaric oxygenation (HBO) combined with corticoid was found effective in several animal studies. Such evidence was obtained for moderate 20-25 dB losses. The aim of this study was to further assess this therapy for noise-induced hearing losses greater than previously examined.

Enhanced cochlear acoustic sensitivity and susceptibility to endotoxin are induced by adrenalectomy and reversed by corticosterone supplementation in rat.

Glucocorticoid receptors are widely distributed in the cochlea but their role remains poorly known. Previous studies provided contradictory reports on a possible cochlear acoustic hypersensitivity induced by adrenal insufficiency, while several experiments agree on a significant action of glucocorticoid receptors in adverse conditions such as acoustic trauma and restraint stress. The present experiments confirmed a cochlear acoustic hypersensitivity induced by adrenalectomy and reversed by corticosterone supplementation.

Stress hormones in Ménière's disease and acoustic neuroma.

Stress has been postulated to trigger or contribute to inner ear pathologies but there is little objective evidence. We investigated stress hormones in Ménière's patients and patients with acoustic neuroma. Data were compared with those from a control group of patients with facial spasm.

Hexachlorobenzene, a dioxin-like compound, disrupts auditory function in rat.

Hexachlorobenzene (HCB) is a dioxin-like compound widely distributed in the environment. In this study, we investigated the effects of HCB on the cochlea. Conscious free-moving rats were given HCB per os daily for 4 weeks at doses of 0.

Stress in hearing and balance in Meniere's disease.

Stress is an unavoidable every-day phenomenon. Physiological coping with stress depends on the appropriate release of stress hormones as well as their alleviation at the termination of the stress. Despite quite a body of research indicating that stress affects inner ear function, this concept has found little application in otolaryngology.

Does repeated hyperbaric exposure to 4 atmosphere absolute cause hearing impairment? Study in Guinea pigs and clinical incidences.

Hypothesis: Direct pressure applied on the inner ear cannot induce hearing loss.

Background: Three possible causes have been described in the literature for inner ear permanent lesions during scuba diving: pressure imbalance between the middle ear and the external ear, appearance of microbubbles in the internal ear, and direct effect of pressure on the inner ear. We seek to determine whether this last factor can be involved.

Similar half-octave TTS protection of the cochlea by xylazine/ketamine or sympathectomy.

Cochlear efferents, sympathetic control and stress conditions have been shown to influence sound-induced hearing loss. These factors are also known to be modified by sedation/anesthesia. We tested here the effect of sedation/anesthesia on temporary threshold shift (TTS) compared to that in the same awake animals.

Prolactinoma in some Ménière's patients--is stress involved?

Dizziness is a common complaint in primary care clinics and can enter the diagnostic profile of different pathologies spanning from psychiatric problems to vestibular dysfunction. Episodes of vertigo in Ménière's patients are often reported to be triggered by stress but no physiological data are available to account for the subjective link. The study involved 42 Ménière's patients hospitalized for neurectomy of the vestibular nerve for relief of incapacitating vertigo.

Onset overmasking of a brief amplitude increment in a pure tone and sensorineural hearing impairment.

Hypothesis: The goal of this investigation was to determine, in patients with sensorineural hearing loss who may show an audiologic alteration in onset overmasking, whether different pathologic conditions differ in this respect, and whether patients with a vestibular neurotomy damaging the cochlear efferents will be affected.

Background: Auditory detection of brief signals, when presented at the beginning of a simultaneous long masking sound, may require a higher acoustic level than when presented after several hundred milliseconds. The proposed explanation, in terms of auditory nerve fibers adaptation has been based on the observation of a proportionally smaller increase of firing in response to an amplitude increment at the onset of a stimulus.

Sympathectomy improves the ear's resistance to acoustic trauma--could stress render the ear more sensitive?

Emotional stress is a phenomenon experienced by many people at some time in their lives. Some of its early manifestations, such as unbearable loudness of ambient sounds and sensations of dizziness, might be linked to inner ear dysfunction. Although the inner ear is supplied with a substantial sympathetic innervation, previous studies have failed to demonstrate any significant functional impact.

Auditory sensori-neural alterations induced by salicylate.

Early after the development of aspirin, almost 150 years ago, its auditory toxicity has been associated with high doses employed in the treatment of chronic inflammatory diseases. Tinnitus, loss of absolute acoustic sensitivity and alterations of perceived sounds are the three auditory alterations described by human subjects after ingestion of large doses of salicylate. They develop over the initials days of treatment but may then level off, fluctuate or decrease, and are reversible within a few days of cessation of treatment.