Scientists have mapped the activity that takes place across a mouse’s entire brain as it decides how to complete a task – and the results could explain the origin of our gut feelings
By Helen Thomson
3 September 2025
A map of a mouse’s brain showing 75,000 neurons
Dan Birman, International Brain Laboratory
The first complete activity map of a mammalian brain has revealed unprecedented insights into how decisions are made – and may even hint at the roots of that mysterious feeling we call intuition.
For decades, neuroscientists have wanted to capture activity across the whole brain at the level of individual neurons – but there is a limit to how many neurons an electrode can record from, how many electrodes can be implanted in a single brain and how many animals a single lab can test.
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To overcome this, researchers across 12 labs have joined forces, each running the same experiment but recording activity from different areas of the brain, with some overlap to ensure the data they collected was consistent. The combined data from more than 650,000 neurons has now produced the first brain-wide activity map of a complex behaviour.
“This work demonstrates a completely new way of tackling complex questions in modern neuroscience,” says Benedetto De Martino at University College London, who wasn’t involved in the research. “Just as CERN [the European Organization for Nuclear Research] brought physicists together to confront the deepest problems in particle physics, this project unites labs worldwide to take on challenges too great for any single group.”
At each lab, mice were trained to move a stripy target towards the middle of a screen using a tiny Lego steering wheel. When the stripes were high contrast, the target stood out clearly. When the contrast diminished, the target all but disappeared, and the animals relied on prior knowledge to answer correctly in order to receive a reward.