Scientists say the map of a speck of a mouse’s brain could be as transformative as the Human Genome Project. Here’s what to know.

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- Scientists created the largest functional map of a brain to date using a piece of a mouse’s brain.
- The map details the wiring that connects neurons, offering insight into brain function and organization.
- Researchers believe this work could eventually lead to treatments for brain disorders like Alzheimer’s, Parkinson’s and schizophrenia.
Scientists have achieved a feat once believed impossible, constructing the largest functional map of a brain to date, which they believe could eventually lead to the discovery of medications for hard-to-treat brain disorders like Alzheimer’s and Parkinson’s disease.
Using a piece of a mouse’s brain no larger than a grain of sand, scientists from across three institutions created a detailed diagram of the wiring that connects neurons as they send messages through the brain.
The project, called Machine Intelligence from Cortical Networks (MICrONS), offers unprecedented insight into the brain’s function and organization that could help unlock the secrets of intelligence.
David Markowitz, a scientist who helped coordinate the project, said the data, published April 9 in the journal Nature marks “a watershed moment for neuroscience, comparable to the Human Genome Project in their transformative potential.”
If you give a mouse YouTube
In the study, scientists looked at a small piece of the mouse’s brain called the neocortex, which receives and processes visual information. It’s the newest part of the brain in terms of evolution, and differentiates the brains of mammals from other animals, according to researchers.
A team of researchers at Baylor College of Medicine in Houston started by recording brain activity in a portion of the mouse’s visual cortex roughly the size of a grain of salt while it watched a series of YouTube clips and movies.
Scientists at the Allen Institute, a research center in Seattle, then sliced that piece of the mouse’s brain into more than 25,000 layers, each a tiny fraction of the width of a human hair, and took high resolution photos of the slices through microscopes. The material was sent to a team at Princeton University, in New Jersey, which used artificial intelligence to reconstruct the pieces in 3D.
Other scientists compared their approach to understanding a car’s combustion engine.
“Just as an engine is composed of pistons, cylinders and a fuel system, the brain consists of neurons and synapses – the tiny, specialized connections at which neurons communicate,” two Harvard researchers wrote in a companion piece to the Nature article.
The data set from the research contains 84,000 neurons, 500 million synapses and neuronal wiring that could extend the length of New York’s Central Park nearly one and a half times, molecular biologists Mariela Petkova and Gregor Schuhknecht wrote.
Findings from the studies have led to discoveries of new cell types, characteristics and ways to classify cells, researchers said. The achievement also puts scientists closer to their larger goal of mapping the wiring of the entire brain of a mouse.
“Inside that tiny speck is an entire architecture like an exquisite forest,” Clay Reid, a senior investigator who helped pioneer this area of study, said in a statement. “It has all sorts of rules of connections that we knew from various parts of neuroscience, and within the reconstruction itself, we can test the old theories and hope to find new things that no one has ever seen before.”
Why it matters
Researchers view wiring diagrams as a foundational step that scientists can build on and, eventually, potentially use to find treatments for brain conditions like Alzheimer’s, Parkinson’s and schizophrenia.
They compare the studies to the Human Genome Project, which created the first complete map of the DNA in every human cell. The Human Genome Project has led to profound advances in drug discovery, treatments and disease screenings and helped pave the way for revolutionary gene therapies to treat certain diseases, including some cancers.
With a functional map of the brain, researchers say they now have the ability to understand the brain’s form and function and have opened up new pathways to study intelligence.
Nuno da Costa, an associate investigator at the Allen Institute, described the data they collected as a “kind of Google map” of the piece of the visual cortex.
“If you have a broken radio and you have the circuit diagram, you’ll be in a better position to fix it,” he said in a statement. “In the future, we can use this to compare the brain wiring in a healthy mouse to the brain wiring in a model of disease.”