A fruit fly larva's brain has 3,016 neurons and now, for the first time, scientists have mapped how they're connected together. This is the largest brain "connectome" every completed. Previously, one of the biggest brains mapped belongs to a roundworm, which only has a few hundred neurons. By comparison, a human brain has 86 billion neurons. From the University of Cambridge:
Current technology is not yet advanced enough to map the connectome of more complex animals such as large mammals. But because all brains involve networks of interconnected neurons, the researchers say that their new map will be a lasting reference for future studies of brain function in other animals.
"All brains of all species have to perform many complex behaviours: for example they all need to process sensory information, learn, choose food, and navigate their environment. In the same way that genes are conserved across the animal kingdom, I think that the basic circuit patterns that drive these fundamental behaviours will also be conserved," said Zlatic.
To build a picture of the fruit fly larva connectome, the team used thousands of slices of the larva's brain imaged with a high-resolution electron microscope, to reconstruct a map of the fly's brain – and painstakingly annotated the connections between neurons. As well as mapping the 3016 neurons, they mapped an incredible 548,000 synapses.
The researchers also developed computational tools to identify likely pathways of information flow and different types of circuit patterns in the insect's brain. They found that some of the structural features are similar to state-of-the-art deep learning architecture.