The work can inform future research on the brain and will inspire new machine learning architectures.
The researchers have completed the most advanced brain map to datethat of an insect, a historic achievement in neuroscience that brings scientists closer to the true understanding of the mechanism of thought, as published in the journal ‘Science’.
The international team led by Johns Hopkins University (USA) and the University of Cambridge (UK) produced an astonishingly detailed diagram that trace every neural connection in the brain of a larval fruit flyan archetypal scientific model with brains comparable to humans.
work probably serve as a basis for future research on the brain and will inspire new machine learning architectures.
«If we want to understand who we are and how we think«Part of that is understanding the mechanism of thought,» explains lead author Joshua T. Vogelstein, a Johns Hopkins biomedical engineer specializing in data-driven projects like connectomics, the study of nervous system connections. -. And the key to that is knowing how neurons connect to each other.»
The most complete and extensive map ever made
He first attempt to map a brain –a 14-year roundworm study begun in the 1970s–resulted in a partial map and nobel prize. Since then, partial connections have been mapped in many systems, including flies, mice, and even humans, but these reconstructions often represent only a small fraction of the total brain.
Complete connections have only been generated from several small species with a few hundred or miles of neurons in their bodies: a roundworm, a sea squirt larva, and a marine annelid larva.
The connector of this equipment of a fruit fly breedingthe larva of ‘Drosophila melanogaster’, is the most complete and extensive map ever made from the brain of an insect. It includes 3,016 neurons and all the connections between them: 548,000.
«50 years have passed and this is the first brain connectome. It’s a flag in the sand that we can do it,» Vogelstein said. Everything has been working until it got to this.»
more than a decade
Map entire brains it is difficult and takes a long time, even with the best modern technology. To obtain a complete picture at the cellular level of a brain it is necessary break it down into hundreds or thousands of individual tissue samplesall of which have to be analyzed with electron microscopes before the laborious process of reconstructing all those pieces, neuron by neuron, into a complete and accurate portrait of a brain.
I was late more than a decade in doing with the breeding of fruit flies. The brain of a mouse is estimated to be a million times larger than that of a baby fruit fly, which means that the possibility of mapping anything resembling a human brain is not likely in the near future, perhaps not even. in our lives.
The team purposely selected the larva of the fruit fly because, for an insect, the species shares much of its fundamental biology with humansincluding a comparable genetic base.
Also has rich learning behavior and decision making, making it a useful model organism in neuroscience. For practical purposes, its relatively compact brain allows it to be imaged and its circuits reconstructed in a reasonable amount of time.
Even so, the work took 12 years at the universities of Cambridge and Johns Hopkins. Imaging alone took approximately one day per neuron.
neuron by neuron
The Cambridge researchers created the high-resolution images of the brain and manually studied them to find individual neurons, rigorously tracing each one of them and relating their synaptic connections.
Cambridge released the data to Johns Hopkins, where the team spent over three years using the original code he created to analyze brain connectivity. The Johns Hopkins team perfected techniques to find clusters of affected neurons in shared connectivity patternsand then he looked at how information could spread through the brain.
In the end, the entire team drew a graph of each neuron and each connection, and classified each neuron by the function it plays in the brain. They found that the most active circuits in the brain were those going to and from neurons in the learning center.
The methods developed by Johns Hopkins are applying any brain connection project, and its code is available to anyone trying to map an even larger animal brain, Vogelstein said, adding that despite the challenges, scientists are expected to take on the mouse, possibly in the next decade. Other teams are already working on a map of the adult fruit fly brain.
Co-first author Benjamin Pedigo, a Johns Hopkins doctoral candidate in biomedical engineering, hopes the team’s code can help reveal important comparisons between adult and larval brain connections. As connectomes are generated from more larvae and other related species, Pedigo hopes that its analysis techniques can better understand variations in brain wiring.
Implications for the human code
The work with fruit fly larvae showed characteristics of circuits that recorded surprisingly to prominent and powerful machine learning architectures. The team hopes that continued study will reveal even more computational principles and may inspire new artificial intelligence systems.
«What we have learned about the code of the fruit fly will have implications for human code Vogelstein points out. That’s what we want to understand: how to write a program that drives a human brain network.»