MECHANISMS OF INTRACOCHLEAR ELECTRICAL STIMULATION

该方案项目的目标是确定和研究机制 它控制着电流、神经反应和知觉表现 卵泡内电刺激的条件。总体战略 的研究方案体现在五个方面的组织 项目，所有这些项目都是密切相关的。项目I处理的是 人工耳廓内电极的设计、制作和表征。一个 将开发用于项目III-V的试验性11触点阵列， 可提供改进的空间定位的新型电极 将设计和表征耳廓内电流，并将其 可能携带更多电荷的电极材料将是 已评估。项目二涉及电场的特性 是由耳壳内电极产生的。CAT的有限元场模型 人类耳蜗会被建造出来，临床上会用来-- 将研究应用电极和实验电极。这些模型将是 通过猫耳蜗电流场的经验测量得到了验证。 项目III试图确定和研究管理单个神经元的机制 对电刺激的反应。神经反应的生物物理模型 将在单细胞的定量研究中开发和评估 听神经和耳蜗前腹侧的放电模式 原子核。要研究的主题包括改变空间的影响 刺激电磁场的几何形状，相关的神经反应 具有刺激波形的时间特征，并检验随机性 神经反应的各个方面。项目四涉及总体反应。 对电刺激的多个神经元件。模型组合 将发展场模型和单电池响应的结果， 他们的预测将在急性生理学研究中进行评估 确定神经群体对电信号的反应。项目V 研究植入动物在执行任务时的心理物理表现 被认为是在听觉系统的外围水平进行编码，然后 进行生理研究以记录单位活动使用相同的 已经被行为学研究过的刺激范式。尝试 根据神经反应预测知觉性能的方法将被开发出来 并进行了评估。将进行项目III-V中的所有动物研究 在螺旋神经节存活好和差的情况下。一个 独立的形态核心允许所有项目将发现与细节联系起来 耳聋患者的耳蜗学研究。建议的可能结果 研究内容包括：(1)对人工耳垢的形态有更深入的了解 电流流动和电流激励机制 听觉神经元，(2)对听觉生理基础的洞察 人工耳蜗术后的知觉表现，(3)方式识别 控制神经的空间延伸和时间精细结构 响应，(4)制定生物物理上合理的方法来 改善个体种植体患者的语音处理器，以及(5) 开发临床使用的优化电极设计。

The objective of this program project is to identify and study mechanisms that govern current flow, neural responses and perceptual performance under conditions of intracochlear electrical stimulation. The overall strategy of the research program is reflected in the organization of the five projects, all of which are strongly interrelated. Project I deals with the design, fabrication, and characterization of intracochlear electrodes. An experimental 11-contact array for use Projects III-V will be developed, novel electrode that may provide improved spatial localization of intracochlear current will be designed and characterized, and advanced electrode materials that may carry more electrical charge will be evaluated. Project II deals with the characterization of electrical fields generated by intracochlear electrodes. Finite-element field models of cat and human cochleas will be constructed, and field patterns for clinically- applied and experimental electrodes will be studied. These models will be validated by empirical measurements of current fields in cat cochleas. Project III seeks to identify and study mechanisms governing single-neuron responses to electrical stimuli. Biophysical models of neural response will be developed and evaluated in quantitative studies of single-cell discharge patterns in the auditory nerve and anteroventral cochlear nucleus. Topics to be studied include the effects of changing the spatial geometry of the stimulating current field, correlating neural responses with temporal features of stimulating waveforms, and examining stochastic aspects of neural responses. Project IV deals with the ensemble response of multiple neural elements to electrical stimulation. Models combining the results of field models and single-cell responses will be developed, and their predictions will be evaluated in acute physiological studies that determine neural population responses to electrical signals. Project V investigates psychophysical performance of implanted animals on tasks thought to be encoded at peripheral levels of the auditory system, then conducts physiological studies to record unit activity using the same stimulus paradigms that had been studied behaviorally. Models that attempt to predict perceptual performance from neural responses will be developed and evaluated. All animal studies in Projects III-V will be conducted under conditions of both good and poor spiral ganglion survival. A separate Morphology Core allows all projects to relate findings to details of cochlear anatomy in deafened ears. Likely outcomes of the proposed research include (1) an improved knowledge of patterns of intracochlear current flow and the mechanisms by which electrical current excites auditory neurons, (2) insight into the physiological basis of auditory perceptual performance with cochlear implants, (3) identification of ways to control the spatial extend and temporal fine structure of neural responses, (4) the formulation of biophysically sound approaches to improving speech processors in individual implant patients, and (5) the development of optimized electrode designs for clinical use.