Optical cochlea stimulation is under investigation as a potential alternative to conventional electric cochlea implants in
treatment of sensorineural hearing loss. If direct optical stimulation of spiral ganglion neurons (SGNs) would be feasible,
a smaller stimulation volume and, therefore, an improved frequency resolution could be achieved. However, it is unclear
whether the mechanism of optical stimulation is based on direct neuronal stimulation or on optoacoustics. Animal studies
on hearing vs. deafened guinea pigs already identified the optoacoustic effect as potential mechanism for intra-cochlear
In order to characterize the optoacoustic stimulus more thoroughly the acoustic signal along the beam path of a pulsed
laser in water was quantified and compared to the neuronal response properties of hearing guinea pigs stimulated with
the same laser parameters. Two pulsed laser systems were used for analyzing the influence of variable pulse duration,
pulse energy, pulse peak power and absorption coefficient.
Preliminary results of the experiments in water and in vivo suggesta similar dependency of response signals on the
applied laser parameters: Both datasets show an onset and offset signal at the beginning and the end of the laser pulse.
Further, the resulting signal amplitude depends on the pulse peak power as well as the temporal development of the
applied laser pulse. The data indicates the maximum of the first derivative of power as the decisive factor. In conclusion
our findings strengthen the hypothesis of optoacoustics as the underlying mechanism for optical stimulation of the
Nicole Kallweit, Peter Baumhoff, Alexander Krueger, Nadine Tinne, Alexander Heisterkamp, Andrej Kral, Hannes Maier, and Tammo Ripken, "Signal and response properties indicate an optoacoustic effect underlying the intra-cochlear laser-optical stimulation," Proc. SPIE 9689, Photonic Therapeutics and Diagnostics XII, 96892G (Presented at SPIE BiOS: February 14, 2016; Published: 1 March 2016); https://doi.org/10.1117/12.2210926.
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