Journal of Innovative Optical Health Sciences, Volume. 10, Issue 5, 1743004(2017)
In vivo auditory nerve stimulation with visible light
Background: Infrared laser stimulation has been proposed as an innovative method to elicit an auditory nerve response. Most studies have focused on using long-wavelength infrared (> 980 nm) pulsed lasers with high water absorption coe±cients. This paper sought to assess whether a shortwavelength laser (465 nm) with an absorption coe±cient as low as 10-3 cm-1 would activate the auditory nerve and studied its potential mechanism. Method: Optical compound action potentials (OCAPs) were recorded when synchronous trigger laser pulses stimulate the cochlea before and after deafening, varying the pulse durations (from 800 μs to 3600 μs) and the amount of radiant energy (from 18.05 mJ/cm2 to 107.91 mJ/cm2). A thermal infrared imager was applied to monitor the temperature change of the guinea pig cochlea. Results: The results showed that pulsed laser stimulation at 465nm could invoke OCAPs and had a similar waveform compared to the acoustical compound action potentials. The amplitude of OCAPs had a positive correlation with the increasing laser peak power, while the latency of OCAPs showed a negative correlation. The imager data showed that the temperature in the cochlea rose quickly by about 0.3C right after stimulating the cochlea and decreased quickly back to the initial temperature as the stimulation ended. Conclusions: This paper demonstrates that 465-nm laser stimulation can successfully induce OCAPs outside the cochlea, and that the amplitude and latency of the invoked OCAPs are highly affected by laser peak power. This paper proposes that a photothermal effect might be the main mechanism for the auditory nerve response induced by short-wavelength laser stimulation.
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Tian Guan, Muqun Yang, Yonghong He. In vivo auditory nerve stimulation with visible light[J]. Journal of Innovative Optical Health Sciences, 2017, 10(5): 1743004
Received: Jul. 15, 2017
Accepted: Aug. 10, 2017
Published Online: Jan. 10, 2019
The Author Email: Guan Tian (guantian@sz.tsinghua.edu.cn)