Scientists have developed the most detailed map of a fruit fly’s brain to date, revealing nearly 140,000 neurons and 54.5 million synapses. This achievement comes after over four years of work by researchers, led by neuroscientists Mala Murthy and Sebastian Seung at Princeton University. The map, known as a ‘connectome’, represents the most complete brain diagram for any organism.
This detailed project used electron microscopy images to reconstruct the fly’s brain. AI-assisted tools helped compile the data, although many parts required manual review. The research team, along with volunteers, made more than three million manual edits to ensure accuracy. These efforts revealed 8,453 neuron types, with 4,581 being newly discovered.

Surprising Discoveries in Neural Connections

During the study, researchers uncovered surprising details about how different neurons are interconnected. They found that neurons typically involved in sensory processing, such as visual circuits, often connect to neurons responsible for other senses, such as hearing and touch. This discovery has highlighted the complex integration of sensory information within the brain.

Insights into Fruit Fly Behaviour

The data collected has already been used to simulate fruit fly behaviour in virtual models. In one experiment, the simulation showed how neurons responsible for detecting sweet or bitter tastes activate motor neurons controlling the fly’s proboscis. When tested on real flies, the virtual model was more than 90% accurate in predicting neuron response and behaviour.

Future Research Potential

Although the map is based on a single female fruit fly, it provides significant insights into brain function and structure. Researchers plan to expand the project to include male flies and study behaviour such as singing. Despite the progress, researchers note that much more remains to be understood about the chemical and electrical communication between neurons.