Princeton University researchers developed an instrument that allowed them to capture among the first 3D recordings of neural activity in nearly the entire brain of a free-moving animal, the nematode Caenorhabditis elegans. The researchers were able to correlate the activity of 77 neurons with specific behaviors in the animals. The video above shows the location of brain-cell nuclei in a nematode's head. (Video courtesy of Andrew Leifer, Lewis-Sigler Institute for Integrative Genomics)