The first brain map of an insect has been completed, a step that represents a “historic achievement for neuroscience” as it brings scientists closer to “truly understanding” the mechanism of thought.
Brains are networks of interconnected neurons, and all brains of all species must perform complex behaviors such as navigating their environment, selecting food, or escaping predators. Now, a team of scientists has managed to complete the first brain map of an insect, a larval vinegar fly.
For those responsible for this discovery, this “landmark achievement” opens the door to the future of brain research and inspires new learning architectures.
The details of the largest complete brain connection [mapa detalhado de conexões neurais no cérebro] described to date were published in the journal scienceEfe news agency reported.
Responsible for this meticulous research, which lasted 12 years, is a team from the universities of Johns Hopkins (United States) and Cambridge (United Kingdom).
“If we want to understand who we are and how we think, part of it is understanding the mechanism of thought,” emphasized Joshua T. Vogelstein, from Johns Hopkins University, for whom the key is to know how neurons are connected to each other.
The first attempt to map a brain—a 14-year study of a roundworm that began in the 1970s—resulted in a partial map and a Nobel Prize.
Since then, some connections have been mapped in many systems, including flies, rodents and even humans, but these reconstructions usually represent only a small fraction of the total brain, explain scientists at the North American university.
Complete connections have been made only by several small species with a few hundred or thousands of neurons: roundworm, larval sea skirt, and larval sea crowns.
“This means that neuroscience has largely operated without circuit maps,” summarizes Marta Zlatic, from the British university. “Without knowing the structure of a brain, we guess how computations are implemented, but now we can begin to understand mechanically how the brain works,” added the scientist.
A complete map of 3016 neurons
Current technology, he points out, is not yet advanced enough to map the connective tissue of higher animals such as large mammals.
However, “all brains are the same—they are networks of interconnected neurons—and all brains in all species must perform many complex behaviors: processing sensory information, learning, choosing actions, navigating their environment, choosing food, recognizing their kin or escape from predators’.
The connective of the young vinegar fly (or fruit fly), the Drosophila melanogaster, is the most complete and extensive map of an insect’s brain. It includes 3016 neurons and all the connections between them: 548,000.
To get a complete picture at the cellular level of a brain, it is necessary to divide it into hundreds or thousands of individual tissue samples, all of which must be analyzed with electron microscopes before the painstaking process of reconstructing the pieces, neuron by neuron, into a complete and accurate portrait of a brain.
The team deliberately chose the vinegar fly larva because, for an insect, the species shares much of its fundamental biology with humans, including a comparable genetic base.
The research took 12 years, with imaging alone taking about a day per neuron. The scientists classified each neuron based on the function it performs and found, for example, that the most active circuits in the brain were those going to and from neurons in the learning center.
The researchers also developed computer tools to identify possible information flow paths and different types of circuits.
“What we learned about the vinegar fly code will have implications for the human code. That’s what we want to understand: how to write a program that commands a human brain network,” Vogelstein emphasized. The methods and codes developed in this project are available to anyone who wants to map an even larger animal brain.
A rodent’s brain is estimated to be a million times larger than that of a young fruit fly, meaning that the possibility of mapping it is unlikely in the near future, although scientists intend to work around the limitation. , possibly in the next decade.