In vivo microendoscopy for imaging deep regions of the brain

对哺乳动物大脑深处的单个细胞进行成像的能力将在基础和临床科学中打开新的研究机会。目前的脑成像技术不能提供组织的高分辨率图像。例如，磁共振成像(MRI)等脑扫描技术只能达到几毫米的分辨率。在这样一个区域内，可能有数千个细胞，每个细胞执行一项独特的任务。尽管现代光学显微镜可以达到观察单个细胞所需的分辨率，但它们只能看到直接放在显微镜镜头前的物体。回想一下，在生物课上发现显微镜载玻片上的细胞是多么令人沮丧！为了创造一种能够在大脑深处成像的方法，也可以观察单个细胞在做什么，需要一种新的光学设备。互联网的繁荣不仅给我们带来了巨大的信息财富，而且推动了电信业在微光学领域取得了重大发展。梯度折射率(GRIN)透镜，其中光由于光学介质的内部变化而被引导，现在制造成本低且尺寸为亚毫米。目前，最小的GRIN镜片直径只有人的头发那么大，大约100微米。与传统透镜不同，GRIN透镜不是研磨成型的，而是通过掺杂玻璃产生的，然后可以挤压到所需的直径。有点像把字母介绍给海边岩石的方法。由于GRIN透镜的尺寸很小，可以用来制造微型内窥镜。基于GRIN透镜的内窥镜将像传统的内窥镜一样能够接触到身体的偏远部位，然而，由于GRIN透镜内窥镜如此小，因此将是微创的。因此，通过结合这些设备的关键特征，将有可能对以前无法接触到的大脑部分中的单个细胞进行成像。

The ability to image individual cells deep within the mammalian brain will open new research opportunities in both basic and clinical science. Current brain imaging techniques do not provide high-resolution images of the tissues. For example, brain scanning techniques such as magnetic resonance imaging (MRI) only achieve a resolution of a few millimeters. Within such an area there may be several thousand cells, each performing a unique task. Although modern light microscopes can achieve the resolution needed to see individual cells they can only visualize objects placed immediately in front of the microscope lens. Recall how frustrating it was in biology class to find the cells on the microscope slide! To create a method capable of imaging deep within the brain, that can also observe what single cells are doing, will require a new optical device. The internet boom has not only brought an enormous wealth of information to our fingertips but has driven the telecommunications industry to achieve significant developments in the area of micro-optics. Gradient refractive index (GRIN) lenses, in which light is guided as a consequence of the internal variations in optical medium, are now produced cheaply and with sub-millimeter dimensions. Currently the smallest GRIN lenses have the diameter of a human hair, around100 microns. Unlike traditional lenses, GRIN lenses are not ground to shape but generated by doping glass that can then be extruded to the desired diameter. A little like the method used to introduce the letters to seaside rock. Due to their tiny dimensions, GRIN lenses can be used to produce miniature endoscopes. GRIN lens based endoscopes will, like a traditional endoscope be able to achieve access to remote parts of the body, however , a GRIN lens endoscope will be minimally invasive as a consequence of being so small. Thus by combining key characteristics of these devices it will be possible to image individual cells within previously inaccessible parts of the brain.