Brain mapping - a milestone in neurobiological research

The study details more than 50 million connections between more than 139,000 neurons — brain cells that are commonly used in neurobiological studies — of fruit flies.

On October 3, scientists recognized an important milestone in neurobiology research when a complete map of the brain of an adult fruit fly was published in the prestigious scientific journal Nature.

This is considered a feat that provides insight into the brains of the entire animal kingdom, including humans.

Brain map of fruit flies. (Photo: nature).

The study details more than 50 million connections between more than 139,000 neurons — brain cells — of fruit flies , a species scientifically known as Drosophila melanogaster , commonly used in neurobiology studies.

The research seeks to decode how the brain works and the signals that indicate brain function is working properly. The work could also pave the way for mapping the brains of other species.

Really understanding how a brain works, whether it's a fruit fly's or another animal's, will certainly provide insight into many things about the brains of other animals, said study co-leader Sebastian Seung, a professor of neuroscience and computer science at Princeton University.

Some researchers find the fruit fly brain, less than 1 mm in circumference, to be an aesthetically pleasing choice for studying animal brains.

Co-leader of the study, neuroscientist Gregory Jefferis, from the University of Cambridge, said the fruit fly brain is a beautiful structure , suitable for research.

The map created by the researchers provides a diagram of the network of connections in the brains of adult fruit flies.

Similar research has previously been done with simpler organisms, such as the worm Caenorhabditis elegans and the larval stage of the fruit fly. Adult fruit flies exhibit more complex behaviors, reflecting the network of connections in the species' brain systems.

One of the key questions to address is how the brain's network of connections, neurons, and connections can lead to animal behavior, said Princeton neuroscientist Mala Murthy, one of the study's co-leaders. Fly brains are an important model system for neuroscience because their brains solve many of the same problems we do… They are capable of complex behaviors like walking and flying, learning and memory, navigation, feeding, and even social interactions, all of which scientists have studied in their labs at Princeton.

One study analyzed the brain circuits involved in walking and found out how flies stop. Another analyzed the taste network and the control circuitry behind behaviors like using their feet to remove dirt from their antennae. The team also studied the visual system, including how flies' eyes process information about motion and color. Together, the researchers created a map that traces the organization of hemispheres and behavioral circuits inside the fly brain.

The team also identified the full set of cell layers in the fruit fly brain, pinpointed different types of neurons and the chemical connections — synapses — between these neurons, and looked at the types of chemicals released by the neurons.

The work was made possible by an international collaborative network of scientists called the FlyWire Consortium.