Wavefront sensor for deep imaging of the brain

 描述（由申请人提供）：光学成像在我们理解大脑功能的努力中具有巨大的前景。光学脑成像的主要挑战是深度和速度。由于强烈的组织散射，光学显微镜在小鼠大脑中的穿透深度和成像速度非常有限。深度和速度的限制使得小鼠大脑活动的大规模体积成像，例如整个小鼠皮质柱的功能成像，超出了当前成像技术的范围。自适应光学（AO）已被证明对于活体脑成像很有价值，并且将对深部脑三光子显微镜产生更大的影响；然而，现有的 AO 技术在对散射小鼠大脑深处进行成像时需要使用荧光信号进行迭代优化，这与大范围深度和视场的大规模体积成像不兼容。该计划将涉及开发一种新型 2 光子 Shack-Hartmann 波前传感器 (2P-SHWS)，用于直接测量散射小鼠大脑深处的光学波前，然后演示所提出的 2P-SHWS 用于小鼠大脑结构和功能体内多光子成像的性能。这项创新基于这样的认识：深层组织成像和深层组织直接波前传感的物理原理本质上是相同的，因为它们都依赖于弹道光子携带的信息，并且它们都需要抑制散射激发光子的贡献。因此，与多光子深层组织成像背后的原理平行，深层组织波前传感也应该通过使用长波长和非线性激励而受益匪浅。该计划的成功完成将提供前所未有的直接波前测量能力，可在整个小鼠新皮质深度（800 至 900 µm 深）内进行直接波前测量，并且在成像过程中更新速率为 1 至 10 Hz（取决于深度）。凭借其深组织波前传感能力、高更新率、相对简单的实施以及零附加光漂白和光毒性，2P-SHWS 非常适合改变我们大规模、体积记录小鼠大脑活动的能力。

 DESCRIPTION (provided by applicant): Optical imaging holds tremendous promise in our endeavor to understand brain functions. The major challenges for optical brain imaging are depth and speed. Due to strong tissue scattering, the penetration depth and imaging speed of optical microscopy in the mouse brain are very limited. The constraints in depth and speed make large scale, volumetric imaging of mouse brain activity, e.g., functional imaging of an entire mouse cortical column, out of reach of current imaging techniques. Adaptive optics (AO) have proven to be valuable for in vivo brain imaging, and will have even larger impact for deep brain 3-photon microscopy; however, existing AO techniques require iterative optimization using fluorescence signal when imaging deep within scattering mouse brains, which is incompatible with large scale, volumetric imaging over a large range of depth and field of view. This program will involve the development of a novel 2-photon Shack-Hartmann wavefront sensor (2P-SHWS) for direct measurement of optical wavefront deep within scattering mouse brain, followed by demonstration of the performance of the proposed 2P-SHWS for in vivo multiphoton imaging of mouse brain structure and function. This innovation is based on the realization that the physical principles for deep tissue imaging and deep tissue direct wavefront sensing are essentially the same because they both rely on the information carried by the ballistic photons, and they both require the suppression of the contributions from the scattered excitation photons. Therefore, parallel to the rationales behind multiphoton deep tissue imaging, deep tissue wavefront sensing should also benefit tremendously by the use of long wavelength and nonlinear excitation. The successful completion of this program will provide the unprecedented capability of direct wavefront measurement throughout the depth of the mouse neocortex (800 to 900 µm deep) and at an update rate of 1 to 10 Hz (depth dependent) during imaging. With its deep tissue wavefront sensing capability, high update rate, relatively simple implementation, and zero additional photobleaching and phototoxicity, 2P- SHWS is ideally positioned to transform our ability for large-scale, volumetric recording of mouse brain activity.