Understanding the Benefits of Infrared Nerve Stimulators for Neural Interfaces

描述(由申请人提供)：神经假体的目标是将神经功能恢复到具有健康系统保真度的条件。然而，当代的神经假体，包括人工耳蜗，无法实现这一目标。这些设备使用电流来刺激神经元，电流在组织中传播，因此不允许刺激集中的神经元群体。因此，高保真的刺激是不可能的。在我们的模型系统--耳蜗中，有人认为，如果能够同时刺激位于电极上的更多离散位置的神经元，人工耳蜗者的表现可以显著提高。使用聚焦光辐射来刺激神经元的设备可能会实现这一点。今天，我们知道红外神经刺激(INS)是可能的，可以达到允许对声音信息进行编码的刺激率，耳蜗内的空间选择性大约是电刺激的五倍，在慢性实验中的单通道刺激至少在六周内没有显示耳蜗功能损害。这里提出的五年计划是我们以前实验的合乎逻辑的进展。其目的包括验证INS的选择性将导致更多的独立通道，证明三通道设备可以在几周内安全地刺激植入的耳蜗，以及证明每个多通道INS可以独立地编码听觉系统所感知的信息。在项目结束时，我们打算为人类提供一个多通道神经接口的原型，这里是一个人工耳蜗。为了确定独立刺激的最小通道间隔，我们将在聋猫身上植入一个三通道装置。下丘的记录将被用来构建空间调谐曲线(STC)。不重叠的STC表示通道的分离。系统地改变刺激源之间的距离，直到在相邻刺激源上获得独立的刺激。通过改变刺激参数，如重复频率、脉冲形状和相邻通道之间的延迟，实验还将提供有关光刺激的时间特性的信息。将三通道装置长期植入猫耳蜗内后的长期刺激将决定其安全性。诱发的听觉反应将被测量，并将提供有关耳蜗功能和安全性的信息。结果将通过组织学进行确认。使用温敏墨水测量将提供有关刺激过程中热负荷的重要信息。在本项目结束时，将根据物理和光学要求构建一个人类光学耳蜗植入物原型。

DESCRIPTION (provided by applicant): The goal for neuroprostheses is to restore neural function to a condition having the fidelity of a healthy system. However, contemporary neural prostheses, including cochlear implants, are not able to achieve this goal. The devices use electrical current to stimulate the neurons, which spreads in the tissue and consequently does not allow stimulation of focused populations of neurons. Therefore, high fidelity stimulation is no possible. In our model system, the cochlea, it has been argued that the performance of cochlear implant users could be increased significantly if more discrete locations of neurons situated along the electrode could be stimulated simultaneously. This might be possible with devices that use focal optical radiation to stimulate neurons. Today we know that infrared neural stimulation (INS) is possible, that stimulation rates can be achieved that allow encoding of acoustic information, that the spatial selectivity in the cochlea is about five times more selective than electrical stimulation, and that single channel stimulation in chronic experiments shows no functional damage of the cochlea over at least six weeks. The five-year project proposed here is a logical progression of our previous experiments. The aims include validating that the selectivity of INS will result in a larger number of independent channels, demonstrating that a three-channel device can safely stimulate an implanted cochlea over several weeks, and showing that each channel of multichannel INS can independently encode information to be perceived by the auditory system. At the conclusion of the project period we intend to present a prototype for a multi-channel neural interface for the human, here a cochlear implant. To determine the minimum channel separation for independent stimulation, we will implant a three-channel device in deaf cats. Recordings from the inferior colliculus will be used to construct spatial tuning curves (STCs). Non-overlapping STCs indicate separation of the channels. The distance between the stimulation sources will be altered systematically until independent stimulation at neighboring stimulation sources is obtained. By varying stimulus parameters such as the repetition rate, the pulse shape, and the delay between neighboring channels, the experiments will also provide information on the temporal properties of optical stimulation. Long-term stimulation after chronic implantation of a three-channel device into a cat cochlea will determine the safety. Evoked auditory responses will be measured and will provide information on cochlear function and safety. Results will be confirmed through histology. Measurements with temperature sensitive ink will provide important information on the heat load during stimulation. At the conclusion of this project, a prototype human optical cochlear implant will be constructed based on the physical and the optical requirements.