Scientists created the first complete map of a bug’s brain.

A team of neuroscience researchers from the University of Cambridge and John Hopkins University has published a study in the journal Science claiming they have identified the synaptic wiring that connects the brain of a fruit fly larva, creating the first ever complete map of a bug’s brain. 

It turns out that the larva’s brain contains as many as 3,016 neurons and 548,000 synapses. The partial connectome of the brain of an adult fruit fly earlier produced 25,000 neurons and 20 million synapses.

According to the study’s authors, cited by the Nature, the brain of a fruit fly larva is pretty similar to a human brain and has specific zones that are responsible for certain functionalities – just like the case of people – one is designed for decision-making, another responds to learning, a third one is for navigation, and so on. 

To create the map, which basically is a diagram of the neural connections or pathways within the brain or nervous system of an organism, the researchers used the brain of a six-hours-old female fruit fly larva.

They imaged the brain during a year and a half by using an electron microscope, generating thousands of visual slices, which were processed with special software.

Imaging a single neuron required about a day, according to a release from the team. 

Another interesting fact is that almost 75 percent of the most well-connected neurons were linked to the brain’s learning center, underscoring its importance. And while the brain had multiple layers with connections between them, it also had shortcuts that skipped layers.

The experiment revealed that in spite of resemblance with the human brain, the bug’s left and right sides of the brain were similar, which is not the case of humans' hemispheres, which have different functions.

Then, it’s worth remembering that a human brain contains 80-110 billion neurons and several hundreds of trillion synapses. Mapping this brain will be a true challenge.

Until now, only three insects have been brain-mapped by scientists – two types of worms and a sea squirt larva.