In situ in vivo and ex vivo study of the aging human brain: towards creating an MRI and histology brain template averaging 100 cases

对正常衰老大脑的研究是使用人们死后捐赠给科学的大脑来完成的，这被称为大脑的体外研究。对体外大脑的显微研究可以了解任何给定区域的结构，这是几项神经科学研究的基础。然而，我们不能用显微镜研究健康活人的大脑。研究活体大脑的一种方法是使用功能强大的机器进行磁共振成像(MRI)，这些机器提供非常高的图像分辨率(7特斯拉MRI扫描仪)。单独使用MRI的缺点是缺乏确定哪些细胞对MRI上的特定对比度(颜色)负责。为了解决这一问题，我们首先使用核磁共振技术(在我们提议的计划中，我们将使用我校解剖学系捐赠者的大脑)进行体外脑研究，然后进行显微镜研究。最后，我们可以使用捐赠者先前的(体内)MRI扫描，通过他们的医疗文件，将我们的体外MRI结果转化为体内MRI结果。我们的研究计划将评估四种不同的方法来保存头部内部的大脑，以获得更好的MRI结果，并将这些结果与脑库使用的最常用的保存方法进行比较，后者将大脑取出，并在装满液体(特殊液体，不会在MRI扫描上产生颜色的特殊液体)的塑料容器中强制对头部外部的大脑进行MRI扫描。非原位扫描大脑会导致组织变形，使其与相应的组织切片和活体扫描的比较复杂化。我们的计划建议部署标准程序来保存和扫描体外和原位的大脑，改进与标本组织学和活体参与者扫描的比较研究。然后，我们的扫描将被用来创建一个带有组织学关联的平均MRI体外原位模板，该模板将是开源的，并可供神经科学界使用。

The study of the normal aging brain is accomplished using brains that people donate to science after they die, which is called ex vivo study of the brain. The microscopic study of ex vivo brains allows to understand the structure of any given region, which is the basis of several neuroscientific research studies. However, we cannot study the brain of healthy living people (in vivo) using microscopy. One method to study the brain in vivo is magnetic resonance imaging (MRI) using powerful machines that provide very high image resolution (7 Tesla MRI scanners). The downside of using MRI alone is the lack of certainty of which cells are responsible for a given contrast (color) on the MRI. To solve this, we study first the brain ex vivo using MRI (in our proposed program we will use the brain of donors of the Anatomy Department of our university), and then microscopy. Finally, we can use previous (in vivo) MRI scans of donors, available through their medical files, to translate our ex vivo MRI findings, to in vivo MRI findings. Our research program will assess four different ways to conserve the brain inside the head for better MRI results and will compare those results against the most utilized way of conservation employed by brain banks, which remove the brains and force the MRI scanning of the brains outside the head (ex situ) inside plastic containers filled with fluid (special fluid that does not produce a color on the MRI scan). Scanning brains ex situ introduces deformations of the tissue that complicate its comparison with the corresponding histology slices and with in vivo scans. Our program proposes the deployment of standard procedures to conserve and scan brains ex vivo and in situ, improving the comparative study with histology of the specimens, and with scans of living participants. Our scans will be then used to create an average MRI ex vivo-in situ template with histological correlates, which will be open-source and available to the neuroscientific community.