The fly brain sheds light on the human thought process

They can walk and fly and males can even sing love songs to attract mates – all with a mind smaller than the head of a pin.

Now, for the first time, scientists investigating the fly’s brain have been able to determine the position, shape and connections of each of its 130,000 cells and 50 million connections.

It is the most detailed analysis of the brain of an adult animal ever undertaken.

A leading brain specialist independent of the new research described the achievement as a “huge leap” in our understanding of our brains.

One of the leaders of the research said it would shed new light on the “mechanism of thought”.

Dr Gregory Jefferys, from the Medical Research Council’s Laboratory of Molecular Biology in Cambridge, told BBC News that we currently have no idea how the network of brain cells in each of our heads enables us to interact with each other and with the world around us. .

“What is communication? How do signals flow through the system that allows us to process information to recognize your face, that allows you to hear my voice and turn those words into electrical signals?”

“Mapping the fly brain is really cool and will help us get a real understanding of how our brains work.”

We have brain or nerve cells that are a million times larger than the fruit flies that have been studied. So how can the wiring diagram of an insect brain help scientists learn how we think?

Images produced by scientists, which were Published in Nature magazineshowed a tangle of wires that is as beautiful as it is complex.

Its shape and structure hold the key to explaining how this tiny organ can carry out so many powerful computational tasks. Developing a computer the size of a poppy seed capable of doing all these tasks is beyond the capacity of modern science.

Another one of the project leaders, Dr Mala Murthy, from Princeton University, said the new wiring diagram, known scientifically as a neural network, would be “transformational for neuroscientists”.

“It will help researchers better understand how a healthy brain works. We hope in the future it will be possible to compare what happens when things go wrong in our brains.”

This view is supported by Dr. Lucia Brito Godolo, leader of the brain research group at the Francis Crick Institute in London, who is independent of the research team.

“Researchers have completed the neural connections of a simple worm with 300 wires and a larvae with 3,000, but having a complete neural network for something with 130,000 wires is an amazing technical achievement that paves the way for finding the neural connections of much larger brains like the mouse, perhaps within several decades.” “

The researchers were able to identify separate circuits for many individual functions and show how they are related.

The wires involved in movement, for example, are located at the base of the brain, while the wires responsible for processing vision are located on the side. There are many more neurons involved in the latter because vision requires much more computational power.

While scientists already knew about the separate circuits, they didn’t know how to connect them together.

Other researchers are already using circuit diagrams, for example, to find out why flies are so difficult to swat.

The vision circuits detect the direction your rolled newspaper is coming from, and pass the signal to the fly’s legs.

But more importantly, it sends a stronger jumping signal to legs facing away from the object of your imminent death. So you can say that they jump far without having to think, i.e. faster than the speed of thinking.

This discovery may explain why the squash fly is rare in humans.

The wiring diagram was created by slicing up the fly’s brain using what is essentially a microscopic cheese grater, photographing each of the 7,000 slices and digitally placing them together. The Princeton team then applied artificial intelligence to extract the shapes and connections of all the neurons. But the AI ​​wasn’t perfect, as researchers still had to manually fix more than three million errors.

This in itself was an artistic tour de force, but the job was only half accomplished. The map itself was meaningless unless there was a description of what each wire was supposed to do, according to Dr Philip Schlegel, also of the Medical Research Council’s Molecular Biology Laboratory.

“This data is a bit like Google Maps but for brains: the raw wiring diagram between neurons is like knowing which structures correspond to which streets and buildings.

“Describing neurons is like adding street and town names, opening times, phone numbers, reviews, etc. to a map. You need both for it to be really useful.”

the The Fly Connectome network is available to any scientist who wishes to use it To guide their research. Dr. Schlegel believes that the world of neuroscience will witness “an avalanche of discoveries in the next two years” thanks to this new map.

The human mind is much larger than that of a fly, and we do not yet have the technology to capture all the information about its wiring.

But researchers believe that perhaps within 30 years it may be possible to have a human neural network. They say the fly brain is the beginning of a new and deeper understanding of how our minds work.

This research was conducted through a large international collaboration of scientists, called the FlyWire Consortium.