Measurement of Basilar Membrane Motion During Round Window Stimulation in Guinea Pigs

Abstract

Driving the cochlea in reverse via the round window membrane (RWM) is an alternative treatment option for the hearing rehabilitation of a nonfunctional or malformed middle ear. However, cochlear stimulation from the RWM side is not a normal sound transmission pathway. The basilar membrane (BM) motion elicited by mechanical stimulation of the RWM is unknown. In this study, the BM movement at the basal turn was investigated in both reverse via RWM drive and acoustic stimulation in the ear canal or forward drive in postmortem isolated temporal bone preparations of guinea pigs. During reverse drive, a magnetcoil was coupled on RWM, and the BM vibration at the basal turn and the movement of the incus tip were measured with laser Doppler vibrometry. During forward drive, the vibration of the incus tip induced by sound pressure in the ear canal resulted in BM vibration and the BM movement at the same location as that in the reverse stimulation was measured. The displacement ratio of the BM to RWM in reverse drive and the ratio of the BM to incus in forward drive were compared. The results demonstrated that the BM response measured in both situations was similar in nature between forward and reverse drives. This study provides new knowledge for an understanding of BM movement induced by reverse drive via the RWM stimulation.

Effect of Endolymphatic Hydrops on Sound Transmission in Live Guinea Pigs Measured with a Laser Doppler Vibrometer

“…The measurement of the stapes head in this study was recorded at a nearby site compared with the incus tip reported previously, both around the incudostapedial joint. The mean stapes head displacement of the control group in this study was in accordance with that reported by Guan and Gan [17] (Figure  4A in their paper) on the whole but was generally higher than that reported by Chen et al [23]. Murakami et al [21] reported that the stapes velocity decreased over 0.4–5.0 kHz in fresh human temporal bones with increased hydrostatic pressure of the inner ear under sound pressure of 114 dB SPL.…”

“…The displacement of the incus tip in guinea pigs under 80 dB SPL acoustic stimulation in the ear canal was reported by Guan and Gan [17] and by Chen et al [23]. The measurement of the stapes head in this study was recorded at a nearby site compared with the incus tip reported previously, both around the incudostapedial joint.…”

Benefits of active middle ear implants in mixed hearing loss: Stapes versus round window

“…Colletti et al proved its beneficial outcome by placing the FMT on the RW . Recently, the basilar membrane response to forward and reverse stimulation was measured using an animal model, and the response was also similar in nature . Average hearing gain in stapes vibroplasty and RW vibroplasty, which is a forward and reverse stimulation, did not differ significantly in our study in accordance with the recent report.…”

Development of the head, pinnae, and acoustical cues to sound location in a precocial species, the guinea pig ( Cavia porcellus )

“…They are also popular models for studies of middle (Guan and Gan, 2011; Lee et al, 2014) and inner (Chen et al, 2014) ear mechanics likely because the guinea pig is audiometrically similar to humans in that they hear sounds over comparable ranges of frequencies (Heffner et al, 1971; Syka et al, 2000). Guinea pigs also share similar pinna features (Greene et al, 2014) as humans–unlike many other commonly used animal models (i.e., cat, chinchilla, bat) with upright, conical pinna, guinea pigs have more oval-shaped, “flattened” ears positioned on either side of the head.…”