The first brain map of an insect was completed, a step that represents a “historic achievement for neuroscience”, as it brings scientists closer to the “true understanding” of 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, choosing food or escaping from predators. Now, a team of scientists has managed to complete the first brain map of an insect, a vinegar fly larva.
For those responsible for this breakthrough, this “landmark achievement” opens the door to the future of brain research and inspires new learning architectures.
The details of what is the largest complete brain connectome [mapa detalhado de conexões neurais no cérebro] described to date have been published in the magazine sciencereported the agency Efe.
Responsible for this meticulous investigation, which lasted 12 years, is a team from Johns Hopkins (United States) and Cambridge (United Kingdom) universities.
“If we want to understand who we are and how we think, part of it is to understand the mechanism of thought”, underlined Joshua T. Vogelstein, from Johns Hopkins University, for whom the key is to know how neurons connect to each other.
The first attempt to map a brain – a 14-year study of a roundworm begun in the 1970s – resulted in a partial map and a Nobel Prize.
Since then, partial connectomes 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 the scientists at the North American university.
Complete connectomes have only been generated from several small species with a few hundred or thousands of neurons: roundworm, sea squirt larva, and marine annelid larva.
“This means that neuroscience has mostly worked without circuit maps”, summarizes Marta Zlatic, from the British university. “Without knowing the structure of a brain, we are guessing at how calculations 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 stresses, is still not advanced enough to map the connectome of higher animals, such as large mammals.
However, “all brains are alike – they are networks of interconnected neurons – and all brains in all species have to perform many complex behaviors: processing sensory information, learning, selecting actions, navigating their environment, choosing food , recognition of their congeners or escape from predators”.
The connectome 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 obtain 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 laborious process of reconstructing the pieces, neuron by neuron, to a complete and accurate portrait of a brain.
The team purposely 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 lasted 12 years, with imaging alone taking approximately one day per neuron. The scientists classified each neuron by the function it performs and found, for example, that the most active circuits in the brain were those that went to and from the 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”, underlined Vogelstein. The methods and codes developed in this work are available to anyone looking to map an even larger animal brain.
It is estimated that the brain of a rodent is a million times larger than that of a juvenile vinegar fly, meaning that the possibility of mapping it is not likely in the near future, although scientists intend to address the limitation. , possibly in the next decade.