Brains are, by design, incredibly dense. Whether a particular brain belongs to a human or a mouse, it features layer upon layer of matter that twists and turns and is almost incomprehensible in its complexity.
Our minds are a little bit mind-boggling.
Which is what makes the video above, produced by Nature, so remarkable. It depicts a 3D model of a little piece of a mouse's brain -- specifically, its retina. And the model is, save for its rainbow-bright colors, a faithful one: It shows the precise shape and location of 950 different cells, including both cell bodies and cell branches (dendrites). Each color represents the branches of a different nerve cell.
So how do you make a model like this? First, you take a mouse's retina and slice it extremely thinly. Then you put those slices under an electron microscope. Then you analyze the images using a computer, assigning different colors to each structure. From there, you let your computer take over. In this case, researchers' software was able to identify not just the shape, but also the volume of each structure in the mouse's retina -- and to identify the synapses, or points at which the different cells connect to each other.
That was only the beginning, though. Some 300 students -- human ones -- also worked on the mouse-mind-mapping project, spending a total of 30,000 hours (!) tracing the path of each neuron. Which allowed the computer to know, in turn, how to fuse the colored sections in its visualization.