Measurement of the Middle Ear Transfer Function in Cat, Chinchilla and Guinea Pig

Décory, Laurent; Franke, R.; Dancer, A.

doi:10.1007/978-1-4757-4341-8_33

Cited by 24 publications

(22 citation statements)

References 10 publications

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“…Simulations show that an intermixture of just 3 nL/s (i.e., ∼3 nL with every respiratory-induced pressure pulsation) was sufficient to account for the loss. This amount seems reasonable based on estimates of RW compliance in the guinea pig estimated to be 0.14 nL/Pa (Décory et al 1990;Wit et al 2003). Considering that respiratory fluctuations are around 0.3 mmHg (∼40 Pa) (Böhmer 1993), each respiratory cycle is calculated to result in a volume displacement of approximately 5.6 nL.…”

Section: Discussionmentioning

confidence: 67%

Perilymph Kinetics of FITC-Dextran Reveals Homeostasis Dominated by the Cochlear Aqueduct and Cerebrospinal Fluid

Salt

Gill

Hartsock

2015

JARO

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Understanding how drugs are distributed in perilymph following local applications is important as local drug therapies are increasingly used to treat disorders of the inner ear. The potential contribution of cerebrospinal fluid (CSF) entry to perilymph homeostasis has been controversial for over half a century, largely due to artifactual contamination of collected perilymph samples with CSF. Measures of perilymph flow and of drug distribution following round window niche applications have both suggested a slow, apically directed flow occurs along scala tympani (ST) in the normal, sealed cochlea. In the p r e s e n t s t u d y , w e h a v e u s e d f l u o r e s c e i n isothiocyanate-dextran as a marker to study perilymph kinetics in guinea pigs. Dextran is lost from perilymph more slowly than other substances so far quantified. Dextran solutions were injected from pipettes sealed into the lateral semicircular canal (SCC), the cochlear apex, or the basal turn of ST. After varying delays, sequential perilymph samples were taken from the cochlear apex or lateral SCC, allowing dextran distribution along the perilymphatic spaces to be quantified. Variability was low and findings were consistent with the injection procedure driving volume flow towards the cochlear aqueduct, and with volume flow during perilymph sampling driven by CSF entry at the aqueduct. The decline of dextran with time in the period between injection and sampling was consistent with both a slow volume influx of CSF (∼30 nL/min) entering the basal turn of ST at the cochlear aqueduct and a CSF-perilymph exchange driven by pressure-driven fluid oscillation across the cochlear aqueduct. Sample data also allowed contributions of other processes, such as communications with adjacent compartments, to be quantified. The study demonstrates that drug kinetics in the basal turn of ST is complex and is influenced by a considerable number of interacting processes.

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Section: Discussionmentioning

confidence: 67%

Perilymph Kinetics of FITC-Dextran Reveals Homeostasis Dominated by the Cochlear Aqueduct and Cerebrospinal Fluid

Salt

Gill

Hartsock

2015

JARO

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“…Middle-ear pressure gains have been measured in chinchilla by Décory et al (1990), Ravicz et al (2010), Slama et al (2010), andRosowski (2013a). Interestingly, the G ME magnitude curve reported by (Ravicz and Rosowski 2013a), shown in Figure 6 (brown trace), has a high-frequency cutoff close to that of the present stapes-velocity magnitudes (red trace) and also substantially higher than the corresponding stapes-velocity measurements made by the same authors (blue trace (Ravicz and Rosowski 2013b); magenta trace ).…”

Section: Middle-ear Pressure Gainmentioning

confidence: 99%

Stapes Vibration in the Chinchilla Middle Ear: Relation to Behavioral and Auditory-Nerve Thresholds

Robles

Temchin²,

Fan³

2015

JARO

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The vibratory responses to tones of the stapes and incus were measured in the middle ears of deeply anesthetized chinchillas using a wide-band acousticstimulus system and a laser velocimeter coupled to a microscope. With the laser beam at an angle of about 40°relative to the axis of stapes piston-like motion, the sensitivity-vs.-frequency curves of vibrations at the head of the stapes and the incus lenticular process were very similar to each other but larger, in the range 15-30 kHz, than the vibrations of the incus just peripheral to the pedicle. With the laser beam aligned with the axis of pistonlike stapes motion, vibrations of the incus just peripheral to its pedicle were very similar to the vibrations of the lenticular process or the stapes head measured at the 40°angle. Thus, the pedicle prevents transmission to the stapes of components of incus vibration not aligned with the axis of stapes piston-like motion. The mean magnitude curve of stapes velocities is fairly flat over a wide frequency range, with a mean value of about 0.19 mm . (s Pa −1 ), has a high-frequency cutoff of 25 kHz (measured at −3 dB re the mean value), and decreases with a slope of about −60 dB/octave at higher frequencies. According to our measurements, the chinchilla middle ear transmits acoustic signals into the cochlea at frequencies exceeding both the bandwidth of responses of auditory-nerve fibers and the upper cutoff of hearing. The phase lags of stapes velocity relative to ear-canal pressure increase approximately linearly, with slopes equivalent to pure delays of about 57-76 μs.

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“…Other authors have discussed the phenomenon of basilar membrane movement resulting from animal experiments with the Mössbauer technique [6], capacitive probe [7] and AEP technique [8]. Among these are examinations involving measurement of the mechanoelectrical transfer function between the auditory canal and the potential measurement electrode [9][10][11]. The pressure measurements in both perilymphatic scales by Franke and Dancer [12] and later by Décory et al [10] complement the data.…”

Section: Introductionmentioning

confidence: 67%

Observations on Simultaneous Perilymphatic Motions and Cochlear Microphonics Suppression

Haberland

Neumann

1999

ORL

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Very low frequencies interfere in the intact cochlea with higher frequencies and suppress these depending on the vibration phase of the low-frequency sound. Physiological functions of the body, mediated, for example, by the eardrum or perilymph coupling with the cerebrospinal fluid, cause a low-frequency pressure modulation of the perilymph, which generates a synchronous perilymphatic motion resulting from the unevenly distributed compliances in the cochlea. This slow streaming causes a displacement of the entire basilar membrane, with as a consequence a postponement of the operating point of the mechanoelectrical transducer as a result of the pressure drop in the helicotrema and the narrow apical cochlear turn. In this contribution, interference phenomena are described, which are caused by spontaneous contractions of the tensor tympani muscle and by respiration-synchronous perilymphatic flow. These two test signals have trapezoidal and triangular impulse functions. In both cases, as suppression pattern of the cochlear microphonics level-time function, the second derivative of the pressure-time function was observed. The suppression is found to lie between 1 and 2 dB. It depends on the level of the suppressed sound and shows a compressive nonlinearity.

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Measurement of the Middle Ear Transfer Function in Cat, Chinchilla and Guinea Pig

Cited by 24 publications

References 10 publications

Perilymph Kinetics of FITC-Dextran Reveals Homeostasis Dominated by the Cochlear Aqueduct and Cerebrospinal Fluid

Perilymph Kinetics of FITC-Dextran Reveals Homeostasis Dominated by the Cochlear Aqueduct and Cerebrospinal Fluid

Stapes Vibration in the Chinchilla Middle Ear: Relation to Behavioral and Auditory-Nerve Thresholds

Observations on Simultaneous Perilymphatic Motions and Cochlear Microphonics Suppression

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