Scientists are one step closer to understanding consciousness, with the unveiling of the world’s first complete, high-resolution brain map of the baby fruit fly. It’s the most complex and intricate connectome of any animal’s brain ever constructed and paves the way for a revolutionary new frontier of artificial intelligence and neuroscience developments.
This new wiring map is the culmination of work between scientists at the University of Cambridge and Johns Hopkins University, and it’s only the fourth complete connectome to date. Previously the much simpler brains of the microscopic roundworm Caenorhabditis elegans, the larval sea squirt Ciona intestinalis and the marine worm Platynereis dumerilii have been mapped, but those featured at most a few hundred neurons and several thousand synapses (connections). And earlier fruit fly connectomes have been partial pictures.
The high-resolution connectome imaging of the larval fruit fly, Drosophilia melanogaster, displays 3,016 neurons and the 548,000 connections between them. It’s been a long time coming for scientists eager to fully map the brain of an insect that shares a lot of fundamental biology with humans.
“It’s been 50 years and this is the first brain connectome. It’s a flag in the sand that we can do this,” said Joshua T. Vogelstein, a Johns Hopkins biomedical engineer. “Everything has been working up to this.”
The landmark work took 12 years to complete, and the acutely intricate processes involved are mind-blowing. First, the team used electron microscopy to visually slice the brain of the six-hour-old female fruit fly larva the size of a grain of salt into not just a few parts but thousands of sections.
While the electron microscope captured an image of each slice, the imaging alone still took a day for each of the 3,016 neurons.
The joint research from Cambridge and Johns Hopkins scientists across fields including neuroscience, microbiology and computer science, saw the fully realized brain map in high definition. The imaging shows every neuron and connection and offers fascinating insights into thought processing and behavior, such as how the busiest circuits led to and away from the brain's learning center.
Fruit flies have complex learning and decision-making behaviors, and they are one of the most studied animals in neuroscience research. What’s more, the map revealed circuit features reminiscent of machine learning architectures, which could even inform new artificial intelligence.
“What we learned about code for fruit flies will have implications for the code for humans,” Vogelstein said. “That’s what we want to understand – how to write a program that leads to a human brain network.”
Scientists are currently working on mapping an adult fruit fly’s brain, eager to compare developmental changes. Vogelstein said research into mapping the brain of a mouse is under way and might be realized within the next decade. But it’s a monumental task, with its size estimated to be a million times larger than that of the larval fruit fly.
Current computational tools can trace millions of neural pathways, but not the trillions the human brain is thought to possess. We’re unlikely to see a complete human connectome – which would likely map out the keys to our complex consciousness – for a very long time.
The research was published in the journal Science. See how the connectome was constructed, and view the final impressive model in the videos below.
Source: Johns Hopkins University
