Faculty Opinions recommendation of Control of hearing sensitivity by tectorial membrane calcium.

Author(s):  
Andrew Chisholm
2019 ◽  
Vol 116 (12) ◽  
pp. 5756-5764 ◽  
Author(s):  
Clark Elliott Strimbu ◽  
Sonal Prasad ◽  
Pierre Hakizimana ◽  
Anders Fridberger

When sound stimulates the stereocilia on the sensory cells in the hearing organ, Ca2+ions flow through mechanically gated ion channels. This Ca2+influx is thought to be important for ensuring that the mechanically gated channels operate within their most sensitive response region, setting the fraction of channels open at rest, and possibly for the continued maintenance of stereocilia. Since the extracellular Ca2+concentration will affect the amount of Ca2+entering during stimulation, it is important to determine the level of the ion close to the sensory cells. Using fluorescence imaging and fluorescence correlation spectroscopy, we measured the Ca2+concentration near guinea pig stereocilia in situ. Surprisingly, we found that an acellular accessory structure close to the stereocilia, the tectorial membrane, had much higher Ca2+than the surrounding fluid. Loud sounds depleted Ca2+from the tectorial membrane, and Ca2+manipulations had large effects on hair cell function. Hence, the tectorial membrane contributes to control of hearing sensitivity by influencing the ionic environment around the stereocilia.


Author(s):  
Roberta M. Bruck

An unusual structure in the cochlea is the spiral limbus; this periosteal tissue consists of stellate fibroblasts and collagenous fibers embedded in a translucent ground substance. The collagenous fibers are arranged in vertical columns (the auditory teeth of Haschke). Between the auditory teeth are interdental furrows in which the interdental cells are situated. These epithelial cells supposedly secrete the tectorial membrane.The fine structure of interdental cells in the rat was reported by Iurato (1962). Since the mouse appears to be different, a description of the fine structure of mouse interdental cells' is presented. Young adult C57BL/6J mice were perfused intervascularly with 1% paraformaldehyde/ 1.25% glutaraldehyde in .1M phosphate buffer (pH7.2-7.4). Intact cochlea were decalcified in .1M EDTA by the method of Baird (1967), postosmicated, dehydrated, and embedded in Araldite. Thin sections stained with uranyl acetate and lead citrate were examined in a Phillips EM-200 electron microscope.


2020 ◽  
Vol 29 (4) ◽  
pp. 738-761
Author(s):  
Tess K. Koerner ◽  
Melissa A. Papesh ◽  
Frederick J. Gallun

Purpose A questionnaire survey was conducted to collect information from clinical audiologists about rehabilitation options for adult patients who report significant auditory difficulties despite having normal or near-normal hearing sensitivity. This work aimed to provide more information about what audiologists are currently doing in the clinic to manage auditory difficulties in this patient population and their views on the efficacy of recommended rehabilitation methods. Method A questionnaire survey containing multiple-choice and open-ended questions was developed and disseminated online. Invitations to participate were delivered via e-mail listservs and through business cards provided at annual audiology conferences. All responses were anonymous at the time of data collection. Results Responses were collected from 209 participants. The majority of participants reported seeing at least one normal-hearing patient per month who reported significant communication difficulties. However, few respondents indicated that their location had specific protocols for the treatment of these patients. Counseling was reported as the most frequent rehabilitation method, but results revealed that audiologists across various work settings are also successfully starting to fit patients with mild-gain hearing aids. Responses indicated that patient compliance with computer-based auditory training methods was regarded as low, with patients generally preferring device-based rehabilitation options. Conclusions Results from this questionnaire survey strongly suggest that audiologists frequently see normal-hearing patients who report auditory difficulties, but that few clinicians are equipped with established protocols for diagnosis and management. While many feel that mild-gain hearing aids provide considerable benefit for these patients, very little research has been conducted to date to support the use of hearing aids or other rehabilitation options for this unique patient population. This study reveals the critical need for additional research to establish evidence-based practice guidelines that will empower clinicians to provide a high level of clinical care and effective rehabilitation strategies to these patients.


1981 ◽  
Vol 24 (1) ◽  
pp. 3-15 ◽  
Author(s):  
Larry E. Humes ◽  
Fred H. Bess

This manuscript examines the issue of potential decline in hearing sensitivity due to hearing aid usage through an analysis of data obtained from the temporary threshold shift (TTS) paradigm. Following a critique of the traditional measures of TTS, the concept of integrated TTS (ITTS) is reviewed and data on hearing-aid-induced ITTS are presented. In addition, a series of equations relating permanent threshold shift (PTS) to a recently developed measure of noise dose (Dn) is derived and predictions for hearing-aid-induced PTS are made. Recommended gain settings established to protect the hearing of a person wearing a hearing aid from further decline following various durations of hearing aid usage are also provided.


1968 ◽  
Vol 11 (1) ◽  
pp. 169-178 ◽  
Author(s):  
Alan Gill ◽  
Charles I. Berlin

The unconditioned GSR’s elicited by tones of 60, 70, 80, and 90 dB SPL were largest in the mouse in the ranges around 10,000 Hz. The growth of response magnitude with intensity followed a power law (10 .17 to 10 .22 , depending upon frequency) and suggested that the unconditioned GSR magnitude assessed overall subjective magnitude of tones to the mouse in an orderly fashion. It is suggested that hearing sensitivity as assessed by these means may be closely related to the spectral content of the mouse’s vocalization as well as to the number of critically sensitive single units in the mouse’s VIIIth nerve.


2017 ◽  
Vol 284 (1864) ◽  
pp. 20171670 ◽  
Author(s):  
Molly C. Womack ◽  
Jakob Christensen-Dalsgaard ◽  
Luis A. Coloma ◽  
Juan C. Chaparro ◽  
Kim L. Hoke

Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans' use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment. We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to high-frequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.


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