Mercer Times

After nine years of work, an international research team has unveiled a detailed map of the vision centers in a mouse brain. This work is the largest and most detailed mapping of neural circuits in a mammal's brain. The map aims to accelerate studies on brain function, such as seeing, memory processing, and navigating environments. This development holds promise for researching diseases linked to neural wiring, including autism and schizophrenia.

"The technologies developed by this project will give us our first chance to really identify some kind of abnormal pattern of connectivity that gives rise to a disorder," said H. Sebastian Seung from Princeton University, co-leader of the project.

The findings were published on April 9 in a special edition of Nature. Alongside Princeton, the project was spearheaded by the Baylor College of Medicine and the Allen Institute for Brain Science, involving over 150 researchers from 22 institutions. Funding came from the U.S. Office of the Director of National Intelligence and the National Institutes of Health. The intelligence office's aim is "to reverse engineer the algorithms of the brain" for machine learning techniques, noting that mammalian brains efficiently make complex decisions with small data sets.

Biologist Francis Crick once remarked in 1979, "It is no use asking [neuroscientists] for the impossible, such as, say, the exact wiring diagram for a cubic millimeter of brain tissue and the way all its neurons are firing." This project has completed that wiring diagram.

The team digitally mapped the mouse brain's more than half a billion connections, integrating structure and function. The activity was measured using calcium ions, indicating information flow, while the mouse was shown video clips.

The mouse brain was sent to the Allen Institute for dissection into 28,000 layers, imaged with an electron microscope, and reconstructed by Seung's team using AI. This final map still requires validation by human proofreading, which continues.

The map is hoped to provide a framework similar to the impact of the Human Genome Project on genomics. "The connectome is the beginning of the digital transformation of brain science," Seung stated, comparing the potential impact of brain mapping technology to that of genomics.

The complete dataset for the mouse brain is publicly available, facilitating worldwide research. Researchers have started mapping the connectomes of species ranging from mosquitoes to humans. Connectomics is expanding rapidly as scientists develop new methods for larger and complex brains.

"We think that every neuroscience experiment should in some ways be referencing a connectome," said Thomas Macrina, from Seung's group, now at Zetta AI.

Connectomics is appreciated for proving its value, validating initial skepticism. J. Alexander Bae noted the demanding effort, but stated, "It was painful. But somehow, we made it happen. I’m in awe."

Despite the achievements, Seung acknowledges the path for connectomics. "It’s just a beginning," he said.