Background: It has been reported that one of the main mechanisms that induces\nthe activation of the cochlea through infrared laser light is the photothermal effect.\nThe temperature in the spiral ganglion cells increases as a result of photon absorption.\nHowever, heat conduction can induce an increase in the temperature within the\ncochlea and change the spatial selectivity of activation.\nMethods: We analyzed the effects of heat conduction on the increase in temperature\nwithin the cochlea using a 3D model that simplifies the spiraled cochlea as a rotational\nsymmetric structure . The model is solved using the finite element method.\nResults: Taken as an example, the cochlea is stimulated by laser pulses at eight sites in\nits first turn. The temperature rise in time domain and spatial domain is simulated\nfor different laser pulse energies and repetition rates. The results demonstrate that\nthe temperature in the cochlea increases as the laser pulse energy and repetition\nrate increase. Additionally, the zone affected by the laser is enlarged because of the\nheat conduction in the surrounding structures. As a result, more auditory neurons\ncan be stimulated than the expected.\nConclusions: The heat conduction affects the laser spatial selectivity however, by\nadjusting the stimulation schemes of the laser pulse-trains, such as laser repetition\nrate and laser power, the laser selectivity can be optimized.
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