High-Frequency Sensitivity of the Mature Gerbil Cochlea and Its Development

Overstreet, Edward H.; Richter, Claus Peter; Temchin, Andrei N.; Cheatham, Mary Ann

doi:10.1159/000067892

Cited by 13 publications

(8 citation statements)

References 38 publications

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“…Cochlear microphonic thresholds subsequently improved rapidly across the responsive frequency range, achieving adult levels by P18 [9]. Although other studies suggest that middle ear and inner ear functions (such as cochlear potentials and basilar membrane mechanics) continue to improve beyond P30 [10], [11], it is generally believed that the gerbil auditory system is functionally and morphologically mature at P18. Although we did not examine gross morphology of the middle ear, our study shows that the development of the ET, which is considered part of the middle ear, occurs before P18.…”

Section: Discussionmentioning

confidence: 99%

Morphology and Ciliary Motion of Mucosa in the Eustachian Tube of Neonatal and Adult Gerbils

Liu

et al. 2014

PLoS ONE

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The Eustachian tube is a small canal that connects the tympanic cavity with the nasal part of the pharynx. The epithelial lining of the Eustachian tube contains a ciliated columnar epithelium at the tympanic cavity and a pseudostratified, ciliated columnar epithelium with goblet cells near the pharynx. The tube serves to equalize air pressure across the eardrum and drains mucus away from the middle ear into the nasopharynx. Blockage of the Eustachian tube is the most common cause of all forms of otitis media, which is common in children. In the present study, we examined the epithelial lining of the Eustachian tube in neonatal and adult gerbils, with a focus on the morphological and functional development of ciliated cells in the mucosa. The length of the tube is ∼8.8 mm in adult gerbils. Scanning electron microscopy showed that the mucosal member near the pharyngeal side contains a higher density of ciliated cells and goblet cells than that near the tympanic side. The cilia beat frequency is 11 Hz. During development, the length of the Eustachian tube increased significantly between postnatal day 1 (P1) and P18. Scanning electron microscopy showed that the mucosa contained a high density of ciliated cells with a few goblet cells at P1. The density of ciliated cells decreased while the density of goblet cells increased during development. At P18, the mucosa appeared to be adult-like. Interestingly, the ciliary beat frequency measured from ciliated cells at P1 was not statistically different from that measured from adult animals. Our study suggests that the Eustachian tube undergoes significant anatomical and histological changes between P1 and P18. The tube is morphologically and functionally mature at P18, when the auditory function (sensitivity and frequency selectivity) is mature in this species.

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Section: Discussionmentioning

confidence: 99%

Morphology and Ciliary Motion of Mucosa in the Eustachian Tube of Neonatal and Adult Gerbils

Liu

et al. 2014

PLoS ONE

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“…A response to airborne sound is first obtained in P12 gerbils, and adult sensitivity occurs at ≈ P30 (Woolf and Ryan, 1984; McGuirt et al, 1995; Huang et al, 1995; McFadden et al, 1996; Overstreet et al, 2003). Compound action potential (CAP) latency and endocochlear potential also mature by ≈P30 (Huang et al, 1995; McGuirt et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

“…The performances of the juvenile groups were then compared with an ‘Adult’ group (n=16) which was trained and tested from P70-P85 (Figure 1A). All data reported in this study were obtained from animals at or beyond the age (postnatal day 30) at which cochlear thresholds are adult-like (Woolf and Ryan, 1984; McGuirt et al, 1995; Huang et al, 1995; McFadden et al, 1996; Overstreet et al, 2003). …”

Section: Methodsmentioning

confidence: 99%

Prolonged maturation of auditory perception and learning in gerbils

Sarro

Sanes

2010

Developmental Neurobiology

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In humans, auditory perception reaches maturity over a broad age range, extending through adolescence. Despite this slow maturation, children are considered to be outstanding learners, suggesting that immature perceptual skills might actually be advantageous to improvement on an acoustic task as a result of training (perceptual learning). Previous non-human studies have not employed an identical task when comparing perceptual performance of young and mature subjects, making it difficult to assess learning. Here, we used an identical procedure on juvenile and adult gerbils to examine the perception of amplitude modulation (AM), a stimulus feature that is an important component of most natural sounds. On average, Adult animals could detect smaller fluctuations in amplitude (i.e. smaller modulation depths) than Juveniles, indicating immature perceptual skills in Juveniles. However, the population variance was much greater for Juveniles, a few animals displaying adult-like AM detection. To determine whether immature perceptual skills facilitated learning, we compared naïve performance on the AM detection task with the amount of improvement following additional training. The amount of improvement in Adults correlated with naïve performance: those with the poorest naïve performance improved the most. In contrast, the naïve performance of Juveniles did not predict the amount of learning. Those Juveniles with immature AM detection thresholds did not display greater learning than Adults. Furthermore, for several of the Juveniles with adult-like thresholds, AM detection deteriorated with repeated testing. Thus, immature perceptual skills in young animals were not associated with greater learning.

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“…A variation of this third approach has been used in recent studies of high-frequency hearing and auditory mechanics in small mammals (Pearce et al, 2001;Overstreet and Ruggero, 2002;Overstreet et al, 2003). In these studies, the stimulus earphone was calibrated against a reference microphone that was coupled to the earphone via an excised ear canal or a short tube of dimensions similar to the ear canal-an "artificial cavity calibration."…”

Section: Introduction a Spatial Variations In Sound Within The Eamentioning

confidence: 99%

Sound pressure distribution and power flow within the gerbil ear canal from 100Hzto80kHz

Ravicz

Olson

Rosowski

2007

The Journal of the Acoustical Society of America

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Sound pressure was mapped in the bony ear canal of gerbils during closed-field sound stimulation at frequencies from 0.1 to 80 kHz. A 1.27-mm-diam probe-tube microphone or a 0.17-mm-diam fiber-optic miniature microphone was positioned along approximately longitudinal trajectories within the 2.3-mm-diam ear canal. Substantial spatial variations in sound pressure, sharp minima in magnitude, and half-cycle phase changes occurred at frequencies >30 kHz. The sound frequencies of these transitions increased with decreasing distance from the tympanic membrane (TM). Sound pressure measured orthogonally across the surface of the TM showed only small variations at frequencies below 60 kHz. Hence, the ear canal sound field can be described fairly well as a onedimensional standing wave pattern. Ear-canal power reflectance estimated from longitudinal spatial variations was roughly constant at 0.2-0.5 at frequencies between 30 and 45 kHz. In contrast, reflectance increased at higher frequencies to at least 0.8 above 60 kHz. Sound pressure was also mapped in a microphone-terminated uniform tube-an "artificial ear." Comparison with ear canal sound fields suggests that an artificial ear or "artificial cavity calibration" technique may underestimate the in situ sound pressure by 5-15 dB between 40 and 60 kHz.

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High-Frequency Sensitivity of the Mature Gerbil Cochlea and Its Development

Cited by 13 publications

References 38 publications

Morphology and Ciliary Motion of Mucosa in the Eustachian Tube of Neonatal and Adult Gerbils

Morphology and Ciliary Motion of Mucosa in the Eustachian Tube of Neonatal and Adult Gerbils

Prolonged maturation of auditory perception and learning in gerbils

Sound pressure distribution and power flow within the gerbil ear canal from 100Hzto80kHz

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