Fiber photometry is widely used in neuroscience labs for in vivo detection of functional fluorescence from optical indicators of neuronal activity with a simple optical fiber. The fiber is commonly placed next to the region of interest to both excite and collect the fluorescence signal. However, the path of both excitation and fluorescence photons is altered by the uneven optical properties of the brain, due to local variation of the refractive index, different cellular types, densities and shapes. Nonetheless, the effect of the local anatomy on the actual shape and extent of the volume of tissue that interfaces with the fiber has received little attention so far. To fill this gap, we measured the size and shape of fiber photometry efficiency field in the primary motor and somatosensory cortex, in the hippocampus and in the striatum of the mouse brain, highlighting how their substructures determine the detected signal and the depth at which photons can be mined. Importantly, we show that the information on the spatial expression of the fluorescent probes alone is not sufficient to account for the contribution of local subregions to the overall collected signal, and it must be combined with the optical properties of the tissue adjacent to the fiber tip.

中文翻译：

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不同脑区解剖特征对光纤光度测量信号空间定位的影响


光纤光度测定广泛应用于神经科学实验室，通过简单的光纤从神经元活动的光学指标中体内检测功能性荧光。光纤通常放置在感兴趣的区域旁边，以激发和收集荧光信号。然而，由于折射率的局部变化、不同的细胞类型、密度和形状，大脑不均匀的光学特性改变了激发光子和荧光光子的路径。尽管如此，到目前为止，局部解剖结构对与纤维接触的组织体积的实际形状和范围的影响还很少受到关注。为了填补这一空白，我们测量了小鼠大脑初级运动和体感皮层、海马体和纹状体中光纤光度测量效率场的大小和形状，强调了它们的子结构如何确定检测到的信号以及光子的深度。可以开采。重要的是，我们表明，仅荧光探针的空间表达信息不足以解释局部子区域对总体收集信号的贡献，它必须与光纤尖端附近组织的光学特性相结合。