Development and Validation of a High-Fidelity Finite-Element Model of Monopolar Stimulation in the Implanted Guinea Pig Cochlea

Goal: To validate a new electroanatomical model of the implanted guinea pig cochlea against independently obtained in vivo voltage tomography data, and evaluate the validity of exist-ing modeling assumptions on current paths and neural excitation. Methods: An in silico model was generated from sTSLIM images and analyzed in COMSOL Multiphysics. Tissue resistivities and boundary conditions were varied to test model sensitivity. Results: The simulation was most sensitive to the resistivities of bone, perilymph, and nerve. Bone tissue in particular should be separated by morphology because different types of bone have different electrical properties. Despite having a strong impact on intrascalar voltages and exit pathways, most boundary conditions, including a new alternative proposed to account for the unmodeled return path, only had a weak effect on neural excitation. Conclusion: The new model demonstrated a strong correlation with the in vivo voltage data. Significance: These findings address a long-standing knowledge gap about appropriate boundary conditions, and will help to promote wider acceptance of insights from computational models of the cochlea.

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