Modular nanophotonic probes for dense neural recording at single-cell resolution

描述（由申请人提供）：在过去的几十年里，我们对单个神经元的特性及其在大脑计算中的作用的理解有了显著的进步。然而，我们还远远不能理解大细胞群是如何相互作用来处理信息的。电生理学是具有无与伦比的时间分辨率的金标准，但目前在记录细胞类型特异性的单个神经元的能力方面受到限制。光学成像提供了一种强大的替代方法，可以通过遗传编码的荧光标记在解剖空间和细胞类型特异性上定位神经元。目前最先进的功能脑成像是双光子荧光激光扫描显微镜。但这种方法只在大脑表面或透明组织上效果最好，而且不容易扩展。更一般地说，光在组织中的散射和吸收有重要的基本限制：在哺乳动物的大脑中，体内可到达的深度仅限于表层皮质区域，1毫米。由于探头直径大（0.3 ~ 0.1 mm），为规避这些限制而开发的内窥镜方法会对成像部位上方的组织造成严重损伤，因此非常有限（例如不能用于研究皮质柱）。在这里，我们提出了一个新的范例，功能性光学成像，超越了这些限制。它允许在高度散射的脑组织中进行细胞分辨率的功能成像，能够在目标体积内完全覆盖所有神经元，并且具有人类应用的长期前景。我们的方法，我们称之为集成神经光子学，是基于在大脑内部分布密集的发射器和检测器像素的三维晶格。这些像素阵列被嵌入到神经光子探针中，实现为可植入的超窄支架，利用了集成纳米光子学的最新进展。与功能性光学报告器（例如GCaMP6）一起使用，一个25柄探针模块将能够以单细胞分辨率记录1- mm3体积（~100,000个神经元）内所有神经元的活动。该方法是可扩展的；多个模块可以平铺在一起，密集地覆盖大脑深处的扩展区域。它最终将允许同时记录大脑中任意位置和深度的数百万个神经元，以揭示完整神经网络的动力学-具有单细胞分辨率和细胞类型特异性。超窄神经光子探针对脑组织的干扰最小，造成的组织位移可以忽略不计，局部功耗很小。重要的是，通过现有的晶圆规模的铸造（工厂）方法，它们很容易生产，因此将广泛用于社区。他们将改变大脑计算和神经精神疾病的电路水平机制的研究，并将通过高通量体内筛选加速药物发现。我们的多学科团队涵盖了所有必要的专业知识：纳米技术和神经光子探针阵列开发的大规模集成（Roukes, Shepard），以及体内测试和计算分析（Tolias, Siapas）。

DESCRIPTION (provided by applicant): Our understanding of the properties of individual neurons and their role in brain computations has advanced significantly during the last few decades. However, we are still very far from understanding how large assemblies of cells interact to process information. Electrophysiology is the gold standard with unmatched temporal resolution, but is currently limited in terms of its ability record from every single neuron withina volume with cell-type specificity. Optical imaging provides a powerful alternative method, which enables localization of neurons in anatomical space and cell-type specificity via genetically encoded fluorescent markers. The current state-of-the-art in functional brain imaging is two-photon fluorescence laser-scanning microscopy. But this approach works best only on the surface of the brain, or transparent tissues and is not easily scalable. More generally, light scattering and absorption in tissue impose significant fundamental limits: in mammalian brains, accessible depths in vivo are restricted to superficial cortical regions, d1mm. Endoscopic methods developed to circumvent such restrictions impart significant damage to tissue above the imaging site given the large probe diameter (0.3 to >1 mm) and thus are quite limited (e.g. cannot be used to study cortical columns). Here we propose a novel paradigm for functional optical imaging that surmounts these limitations. It permits function- al imaging with cellular resolution in highly scattering brain tissue, enables complete coverage of all neurons within a target volume, and has long-term prospects for human applications. Our approach, which we term integrated neurophotonics, is based on distributing a dense 3-D lattice of emitter and detector pixels within the brain itself. These pixel arrays are embedded onto neurophotonic probes, realized as implantable, ultra narrow shanks that leverage recent advances in both integrated nanophotonics. Used with functional optical reporters (e.g. GCaMP6), one 25-shank probe module will be capable of recording the activity of all neurons within a 1- mm3 volume (~100,000 neurons) with single cell resolution. The methodology is scalable; multiple modules can be tiled to densely cover extended regions deep within the brain. It will ultimately permit simultaneous recording from millions of neurons at arbitrary positions and depths in the brain, to unveil the dynamics of complete neural networks - with single-cell resolution and cell-type specificity. Ultra-narrow neurophotonic probes will perturb brain tissue minimally, imposing negligible tissue displacement and minute local power dissipation. Importantly, they are readily producible though existing wafer-scale foundry (factory) based methods and thus will be widely available for use by the community. They will transform studies of circuit- level mechanisms of brain computation and neuropsychiatric disorders, and will accelerate drug discovery via high throughput in vivo screening. Our multi-disciplinary team spans all requisite expertise: nanotechnology and large-scale-integration for development of neurophotonic probe arrays (Roukes, Shepard), and in vivo testing and computational analysis (Tolias, Siapas).