After 12 years of work, a massive team of researchers from the UK, US and Germany has completed the largest and most complex brain map yet, describing every neural connection in the brain of a fruit fly larva.
Although it is nowhere near the size and complexity of the human brain, it still covers a respectable 548,000 connections between a total of 3,016 neurons.
The maps identify the different types of neurons and their pathways, including the interactions between the two sides of the brain and between the brain and spinal cord. This brings scientists closer to understanding how signal movements from neuron to neuron lead to behavior and learning.
“If we want to understand who we are and how we think, part of that is understanding the mechanism of thinking,” He says Joshua T Vogelstein, a biomedical engineer at Johns Hopkins University.
“The key to this is figuring out how neurons communicate with each other.”
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To create this wonderful multifunctional map, called a neural network, the researchers Scanning thousands of slices of a fruit fly’s brain With a high resolution electron microscope. They then stitched the images together and added them to the data they had already collected, placing precise tags on each connection between neurons.
This includes both cells that talk to each other within each hemisphere of the brain as well as those that communicate between the two hemispheres, making it possible to study interactions across the brain in depth.
The two hemispheres of the brain have unique and important functions, but how information from each side is integrated and used for complex behavior and cognition is not well understood.
“The way the brain circuit is organized affects the computational operations that the brain can perform.” Explain Neuroscientist Marta Zlatek of the University of Cambridge.
“But up until this point, we haven’t seen the structure of any brain except the roundworm Certain types are elegant, the tadpole of a lower chordate, and the larva of a marine annelid worm, all containing several hundred neurons. “
Recently, scientists have made great progress in mapping the human brain, tracking neural activity in mice, but the focus has been on specific regions and current technology is still not advanced enough to complete a neural network for larger animals like humans.
However, Zlatic ExplainAll brains are the same — they are all networks of interconnected neurons — and all brains of all kinds must perform many complex behaviors: they all need to process sensory information, learn, choose actions, navigate their environments, choose food, recognize properties, escaping from predators etc.”
fruit flies (Drosophila melanogaster) are a popular scientific research model due to their easy-to-study characteristics, their complex but compact brains, and because they share many biological similarities with us humans.
Notably, the connected structures the researchers observed are determined to be more frequent between the incoming and outgoing neurons in the part of the brain that allows us to learn and remember what we’ve learned.
They also found that some specific features work in a similar way to some machine learning computer networks.
“What we have learned about the code of fruit flies will have implications for the code for humans,” States Vogelstein. “This is what we want to understand – how to write a program that leads to the human brain network.”
The team suggests that the next step will be to learn more about the neural structure involved in certain behavioral functions, such as learning and decision-making, and to look at the activity of the entire neural network while the insect is engaged in the activity.
The first attempt to map the brain was a 14-year study C. elegans that started in the seventies. It yielded an incomplete map of the roundworm’s brain and finally got scientists into A Nobel prize.
“It’s been 50 years and this is the first brain neural network. It’s science in the sand that we can do this,” Vogelstein said. He says.
“Everything works so far.”
The research has been published in the journal Sciences.