Wavefront sensor for deep imaging of the brain

 描述(申请人提供)：光学成像在我们努力了解大脑功能方面有着巨大的希望。光学脑成像的主要挑战是深度和速度。由于组织的强散射，光学显微镜在小鼠脑内的穿透深度和成像速度非常有限。深度和速度上的限制使得对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)已被证明对活体脑成像具有重要价值，并将对脑深部三光子显微镜产生更大的影响；然而，现有的自适应光学技术需要在散布的小鼠大脑深处成像时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。该计划将包括开发一种新型的双光子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，然后展示拟议的2P-SHWS用于在体多光子成像小鼠脑结构和功能的性能。这一创新是基于这样一种认识，即深部组织成像和深部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，并且都需要抑制散射激发光子的贡献。因此，与多光子深部组织成像的原理类似，深部组织波前传感也将因使用长波和非线性激发而受益匪浅。该项目的成功完成将提供前所未有的能力，在整个小鼠新皮质深度(800至900微米深)进行直接波前测量，并在成像过程中以1至10赫兹(取决于深度)的更新速率进行测量。凭借其深层组织波前传感能力、高更新率、相对简单的实现以及零额外的光漂白和光毒性，2P-SHWS是改变我们大规模、体积记录小鼠脑活动的能力的理想定位。

 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.