By studying a basic organism called the nematode C, which is a tiny worm that is usually found in rotting soil, researchers at the Campus Vienna Biocenter in Austria were able to figure out a way to formulate a functional map of the creature's entire nervous system. The nematode C, which is equipped with a sparse 302 neurons and about 8,000 synapses, is currently the only animal that has its complete nervous system anatomically mapped, which makes it easier to use in experiments (and also a good way to avoid PETA).
Using a technique that manipulates light waves to create "discs" of light in a sample, scientists are able to capture multiple dimensions in one go, speeding up the imaging process considerably, according to quantum physicist Robert Prevedel. It also allows them to create 3D videos of the worm's brain activity, which display the movements of a large number of the worm's neurons as time progresses.
Before, scientists were only able to study the activities of one single neuron at a time, making it a slow and tiresome process, as each complete image of a neuron's activity required an image scan under a microscope three separate times. They were also never able to completely map out the creature's entire nervous system due to the limits of their previous imaging technology, which allowed single cells to be analyzed with accuracy but didn't allow for simultaneous viewing of the entire brain's nervous system.