Probing the cochlea with partial tripolar stimulation in cochlear implantees

描述（由申请人提供）：耳蜗植入物是非常成功的神经假体，可增强或恢复严重听力受损者的听力。然而，人工耳蜗的性能在不同的听众之间有很大的差异，特别是在嘈杂的环境中，以及对于像音乐这样的频谱复杂的刺激。病理学和成像研究表明，两个来源的性能变异性的生存螺旋神经节神经元的分布和它们的距离个别CI电极。拟议的研究的目的是开发临床上有用的程序，以确定非刺激区域的耳蜗。由此产生的功能地图可以指导生产的患者特定的声音处理策略，从而提高人工耳蜗植入者的听觉能力。将进行三种类型的心理物理和电生理实验，以确定低功能耳蜗植入通道的位置。所有实验将使用一种新的电极配置，部分三极，激活有限的神经元群体，类似于使用窄带刺激评估听力受损的听众的低功能声学死区。部分三极配置是宽单极和窄三极配置之间的混合，其中可以调整流到两个侧翼电极的电流的分数以改变耳蜗中的电流的传播。在第一个实验中，随着部分三极分数电流的变化，将在植入物阵列上测量检测阈值。当电流场较窄时，将从具有相对高阈值的通道推断低功能通道，并且阈值随分数电流的变化将提供关于功能缺陷的空间范围的信息。在第二个实验中，心理物理调谐曲线将获得使用前掩蔽程序，以提供更详细的评估耳蜗激活。与应用调谐曲线诊断声学死区类似，将测量调谐曲线的宽度和尖端位移，作为识别低功能耳蜗植入通道的一种方式。在第三个实验中，将记录诱发电位。诱发电位阈值和振幅增长函数将直接比较心理物理阈值和调谐曲线获得不同的部分三极电流分数。一个显著的相关性表明，诱发电位程序，这是一个临床实用的技术，可以检测到低功能通道。最终，这项研究的结果可能会导致一个患者特定的映射程序，可用于临床的发展。超过60，000名患有严重听力损失的人已经安装了人工耳蜗以恢复某些听觉能力。在拟议的研究中识别出低功能的人工耳蜗通道可能会增强这些患者的语音和音乐感知。

DESCRIPTION (provided by applicant): Cochlear implants are highly successful neural prostheses that enhance or restore hearing to the severely hearing impaired. However, performance varies considerably among cochlear implant listeners, particularly in noisy environments and for spectrally complex stimuli like music. Pathology and imaging studies suggest that two sources of performance variability are the distribution of surviving spiral ganglion neurons and their distance from individual CI electrodes. The objective of the proposed study is to develop clinically useful procedures to determine non-stimulable regions of the cochlea. The resulting functional maps could guide the production of patient-specific sound processing strategies, leading to improvements in the auditory ability of cochlear implant listeners. Three types of psychophysical and electrophysiological experiments will be conducted to identify the location of low functioning cochlear implant channels. All experiments will use a novel electrode configuration, partial tripolar, to activate restricted populations of neurons, analogous to the use of narrowband stimuli for assessing low functioning acoustic dead regions in hearing impaired listeners. The partial tripolar configuration is a hybrid between the broad monopolar and narrow tripolar configurations, in which the fraction of current that flows to two flanking electrodes can be adjusted to change the spread of current in the cochlea. In the first experiment, detection thresholds will be measured across the implant array as the partial tripolar fractional current varies. Low functioning channels will be inferred from channels with relatively high thresholds when the current field is narrow and the change in threshold with fractional current will provide information about the spatial extent of the functional deficit. In the second experiment, psychophysical tuning curves will be obtained using a forward masking procedure to provide a more detailed assessment of cochlear activation. Similar to the application of tuning curves to diagnose acoustic dead regions, the widths and tip shifts of the tuning curves will be measured as a way to identify low functioning cochlear implant channels. In the third experiment, evoked potentials will be recorded. Evoked potential thresholds and amplitude growth functions will be directly compared to psychophysical thresholds and tuning curves obtained with different partial tripolar current fractions. A significant correlation will suggest that the evoked potential procedure, which is a clinically practical technique, can detect low functioning channels. Ultimately, the findings of this study may lead to the development of a patient-specific mapping procedure that can be used clinically. Over 60,000 people with severe hearing loss have been fitted with cochlear implants to restore some auditory capabilities. Identifying low functioning cochlear implant channels in the proposed study could lead to the enhancement of speech and music perception in these patients.