How Brains See Movement Researchers mapped mouse and fly brains in so much detail that they were able to reconstruct the interconnections neurons were making and (in the fly-brain study) figured out how they were detecting movement. It turns out there are neurons to detect up,down,left and right for flies and the previous mapping of the brain showed how those signals were detected.
To create the mouse brain connectome, they sliced a small section of brain consisting of over 900 nerve cells (about 3x that of the fly brain) into super-thin images and reconstructed it with computers and some help from humans. As you can see it is very intricate and this is only a small portion of a brain which is many times smaller than a humans. Plus this is only 0.06% of the retina, so mapping entire human brains might be a while from now but we do have things like Eyewire where anyone can help map them.