Improved binaural stimulation strategy for bilateral cochlear implants

 描述(申请人提供)：双侧人工耳蜗(CI)使用者对现代CI处理器中用作载波的高速率周期性脉冲串(&gt；30pps)的耳间时间差(ITD)的感知敏感度较差。因此，对于依赖于双耳提示的任务，例如噪声环境中的声音定位和语音接收，CI性能会降低。因此，需要新的CI处理策略来提高知觉ITD的敏感度。在高频率脉冲序列中引入双耳相干抖动已被证明可以提高CI使用者的ITD敏感性，并且在下丘(IC)观察到这种影响的神经关联。IC中的神经元对高频率周期性脉冲串的反应较弱，ITD敏感性较差，但抖动的脉冲串包含偶尔发出的脉冲间间隔(IPI)，可在适应神经元中诱发尖峰，从而增加纤颤频率并恢复ITD敏感性。在这项建议中，我们将测试一种新的加工策略的概念，该策略旨在通过双边CI提高知觉和神经ITD敏感性。在该策略中，额外的脉冲被插入到周期性脉冲序列中，以在刺激中的特定时间点引入短的IPI。在目标1中，我们将使用双侧顺式脑缺血的清醒动物模型来确定短IPIs对IC神经元ITD敏感性的影响。我们的初步数据表明，短IPI可以提高神经ITD的敏感性，我们将调查短IPI的哪些刺激参数能在整个IC神经元群体中优化这种改善。在目标2中，我们将在由语音包络幅度调制的脉冲序列中引入短的IPI，以近似于临床CI处理器所传递的刺激。我们将再次在我们的动物模型中表征IC神经元对神经ITD的敏感性，这将使我们能够研究如何将短IPI纳入临床刺激策略。初步数据显示，较短的IPI可以通过调制脉冲串增加神经ITD的敏感性。最后，在目标3中，我们将在我们的动物模型中用一个经典的条件反射任务来评估短IPIs对知觉性ITD辨别的影响。我们预测，当包含短的IPI时，动物将更容易区分高速脉冲串的ITD。这些实验的总体目标是评估一种新的刺激策略的潜力，该策略使用短的IPI来提高知觉性ITD的敏感性。这一策略可以通过改善嘈杂环境中的声音定位和语音接收来为CI用户带来更好的结果。

 DESCRIPTION (provided by applicant): Bilateral cochlear implant (CI) users have poor perceptual sensitivity to interaural time differences (ITD) of high-rate periodic pulse trains (>30 pps), which are used as carriers in modern CI processors. As a result, CI performance is degraded for tasks that are dependent on binaural cues such as sound localization and speech reception in noisy environments. Therefore, there is a need for new CI processing strategies that improve perceptual ITD sensitivity. Introducing binaurally coherent jitter into high-rate puls trains has been shown to improve ITD sensitivity in CI users, and neural correlates of this effect have been observed in the inferior colliculus (IC). Neurons in the IC respond weakly and with poor ITD sensitivity to high-rate periodic pulse trains, but jittered trains contain occasional shot inter-pulse intervals (IPIs) that can elicit spikes in adapted neurons, thereby increasing the firig rate and restoring ITD sensitivity. We will test the concept of a new processing strategy in this proposal aimed at improving both perceptual and neural ITD sensitivity with bilateral CI. In this strategy, extra pulses are inserted into periodic pulse trains to introduce short IPIs at specific time points in the stimulus. In Aim 1, we will determine the effect of short IPIs on ITD sensitivit of IC neurons using an awake animal model of bilateral CIs. Our preliminary data suggest short IPIs can improve neural ITD sensitivity, and we will investigate what stimulus parameters of short IPIs optimize this improvement across the population of IC neurons. In Aim 2, we will introduce short IPIs into pulse trains that are amplitude modulated by speech envelopes to approximate the stimuli delivered by clinical CI processors. We will again characterize neural ITD sensitivity in IC neurons in our animal model, which will allow us to investigate how short IPIs could be incorporated into a clinical stimulation strategy. Preliminary data suggest short IPIs can increase neural ITD sensitivity with modulated pulse trains. Lastly, in Aim 3 we will evaluate the effect of short IPIs on perceptual ITD discrimination with a classical conditioning task in our animal model. We predict that the animals will more readily discriminate the ITD of high-rate pulse trains when they contain short IPIs. The overall goal of these experiments is to evaluate the potential for a novel stimulation strategy that uses short IPIs to improve perceptual ITD sensitivity. This strategy could lead to better outcomes for CI users by improving sound localization and speech reception in noisy environments.