Spelman F A, Pfingst B E, Clopton B M, Jolly C N, Rodenhiser K L
Center for Bioengineering, University of Washington, Seattle, USA.
Ann Otol Rhinol Laryngol Suppl. 1995 Sep;166:131-6.
Potential distributions measured within the scala tympani of the anesthetized guinea pig support the assertion that focusing is possible when currents are appropriately delivered to the electrodes in the scala tympani. Results obtained with a lumped-element model agree with measurements made in the inner ears of monkeys during monopolar and bipolar stimulation. The predictions are closer for potential distributions apical to the stimulating electrode than they are for basal distributions. In one monkey, in which electrodes were implanted in the middle ear as well as in the inner ear, we obtained measurements of the impedance from inside the scala tympani to points within the middle ear. These impedances are smaller that those initially used in the model, in which the round window membrane was assumed to have a relatively high impedance. A model of the common ground configuration was developed using finite electrode impedances. Finite impedances broaden the potential distributions in this model. Potential distributions from the lumped element model are compared with those obtained with an analytical model, to suggest ways in which focused and unfocused stimuli can affect the excitation of neurons in the implanted ear.
当电流以适当方式施加到鼓阶中的电极时，聚焦是可行的。用集总元件模型获得的结果与在单极和双极刺激期间在猴子内耳中进行的测量结果一致。对于刺激电极顶端的电位分布，预测结果比基底分布的预测结果更接近。在一只猴子中，电极被植入中耳以及内耳，我们获得了从鼓阶内部到中耳内各点的阻抗测量值。这些阻抗比模型最初使用的阻抗小，在该模型中，圆窗膜被假定具有相对较高的阻抗。使用有限电极阻抗开发了共地配置模型。有限阻抗拓宽了该模型中的电位分布。将集总元件模型的电位分布与通过解析模型获得的电位分布进行比较，以提出聚焦和非聚焦刺激影响植入耳中神经元兴奋的方式。
