Infrared Laser Stimulation of Cochlear Nerve through a Tympanic Membrane

Tamai, Yuta; Horinouchi, Kensuke; Hiryu, Shizuko; Kobayasi, Kohta I.

doi:10.1109/lifetech.2019.8884023

Cited by 6 publications

(17 citation statements)

References 12 publications

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“…The repetition rate of the laser stimuli was 100 Hz. The laser was presented 100 times via an optical fiber (diameter, 100 μm; NA, 0.22) and inserted mediolaterally into the left outer ear canal using a micromanipulator (MM-3, Narishige, Tokyo, Japan) as described in earlier reports (Tamai et al, 2019;Tamai et al, 2020). The tip of stimulation fiber was set at around 0.7 mm in front of the tympanic membrane to ensure that the cochlea was irradiated transtympanically from the outer ear (Fig.…”

Section: Laser Stimulimentioning

confidence: 99%

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Feasibility evaluation of transtympanic laser stimulation of the cochlea from the outer ear

Uenaka

Nagamura

Okamoto

et al. 2022

The Journal of the Acoustical Society of America

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Infrared laser stimulation has been studied as an alternative approach to auditory prostheses. This study evaluated the feasibility of infrared laser stimulation of the cochlea from the outer ear, bypassing the middle ear function. An optic fiber was inserted into the ear canal, and a laser was used to irradiate the cochlea through the tympanic membrane in Mongolian gerbils. A pulsed infrared laser (6.9 mJ/cm2) and clicking sound (70 peak-to-peak equivalent sound pressure level) were presented to the animals. The amplitude of the laser-evoked cochlear response was systematically decreased following insertion of a filter between the tympanic membrane and cochlea; however, the auditory-evoked cochlear response did not decrease. The filter was removed, and the laser-evoked response returned to around the original level. The amplitude ratio and the relative change in response amplitude before and during filter insertion significantly decreased as the absorbance of the infrared filter increased. These results indicate that laser irradiation could bypass the function of the middle ear and directly activate the cochlea. Therefore, laser irradiation from the outer ear is a possible alternative for stimulating the cochlea, circumventing the middle ear.

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Section: Laser Stimulimentioning

confidence: 99%

“…The cochlear microphonic (CM) and compound action potential (CAP) were separated according to their latency as described in earlier reports (Izzo et al, 2006;Tamai et al, 2019;Tamai et al, 2020;Teudt et al, 2011). The delays from stimulus onset to the first peak of the CM and CAP responses were measured.…”

Section: Data Analysesmentioning

confidence: 99%

Feasibility evaluation of transtympanic laser stimulation of the cochlea from the outer ear

Uenaka

Nagamura

Okamoto

et al. 2022

The Journal of the Acoustical Society of America

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“…The position of the optic fiber was controlled with a micromanipulator (MM-3, Narishige, Tokyo, Japan). The laser stimulation was performed as described in previous studies including ours [21,56]. The head of the animal was oriented so that the sagittal suture is aligned with the horizontal plane.…”

Section: Laser Stimulimentioning

confidence: 99%

“…The sound pressure level of the sound that is generated by the optoacoustic effect reached 19 dB SPL when measured at maximum intensity (i.e., 12.8 mJ/cm 2 ) at 2 mm from the laser fiber tip. Our previous research assured that continuous laser irradiation with that maximum intensity for 1 h did not cause any thermal damage on the gerbil's cochlea and tympanic membrane [56]. The voltage commands for the laser stimuli were generated using a digital-to-analog converter (Octacapture, Roland, Shizuoka, Japan).…”

Section: Laser Stimulimentioning

confidence: 99%

Auditory cortical activity elicited by infrared laser irradiation from the outer ear in Mongolian gerbils

et al. 2020

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Infrared neural stimulation has been studied for its potential to replace an electrical stimulation of a cochlear implant. No studies, however, revealed how the technic reliably evoke auditory cortical activities. This research investigated the effects of cochlear laser stimulation from the outer ear on auditory cortex using brain imaging of activity-dependent changes in mitochondrial flavoprotein fluorescence signal. An optic fiber was inserted into the gerbil's ear canal to stimulate the lateral side of the cochlea with an infrared laser. Laser stimulation was found to activate the identified primary auditory cortex. In addition, the temporal profile of the laser-evoked responses was comparable to that of the auditory responses. Our results indicate that infrared laser irradiation from the outer ear has the capacity to evoke, and possibly manipulate, the neural activities of the auditory cortex and may substitute for the present cochlear implants in future.

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“…Since humans have a thicker tympanic membrane than gerbils (30-90 µm;Lim, 1970), this could be associated with a greater risk of damage to the tympanic membrane. Although our previous study demonstrated that continuous transtympanic membrane laser irradiation at 12.8 mJ/cm 2 for 1 h did not result in observable damage to the tympanic membrane in gerbils (Tamai et al, 2019), safety evaluation using a human tympanic membrane must be performed prior to the practical application of infrared laser stimulation in auditory prostheses.…”

Section: Discussionmentioning

confidence: 95%

Feasibility evaluation of transtympanic laser stimulation of the cochlea from the outer ear

Uenaka

Nagamura

Hiryu

et al. 2021

Preprint

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Infrared laser stimulation has been studied as an alternative approach to auditory prostheses. This study evaluated the feasibility of infrared laser stimulation of the cochlea from the outer ear bypassing the middle ear function. An optic fiber was inserted into the ear canal and a laser was used to irradiate the cochlea through the tympanic membrane in Mongolian gerbil. A pulsed infrared laser (10.1 mJ/cm2) and clicking sound (70 peak-to-peak equivalent sound pressure level) were presented to the animals. The amplitude of the laser-evoked cochlear response was systematically decreased following insertion of a filter between the tympanic membrane and cochlea; however, the auditory-evoked cochlear response did not decrease. The filter was removed and the laser-evoked response returned to around the original level. The amplitude ratio and the relative change in response amplitude before and during filter insertion significantly decreased as the absorbance of the infrared filter increased. These results indicate that laser irradiation could bypass the function of the middle ear and directly activate the cochlea. Therefore, an auditory prosthesis based on laser stimulation represents a possible noninvasive alternative to conventional auditory prostheses requiring surgical implants.

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Infrared Laser Stimulation of Cochlear Nerve through a Tympanic Membrane

Cited by 6 publications

References 12 publications

Feasibility evaluation of transtympanic laser stimulation of the cochlea from the outer ear

Feasibility evaluation of transtympanic laser stimulation of the cochlea from the outer ear

Auditory cortical activity elicited by infrared laser irradiation from the outer ear in Mongolian gerbils

Feasibility evaluation of transtympanic laser stimulation of the cochlea from the outer ear

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