A group of neuroscientists, including researchers from UCLA Health, has produced the first comprehensive map of brain activity in mice. The work, conducted by the International Brain Laboratory (IBL), was published in two papers in Nature and offers new insights into how decision-making processes occur across the entire brain at the level of individual cells.
The research involved recording neural activity from over half a million neurons across 279 brain areas, covering 95% of the mouse brain volume. “This is the first time anyone has produced a full, brain-wide map of the activity of single neurons during decision-making. The scale is unprecedented as we recorded from over half a million neurons across mice in 12 labs, covering 279 brain areas, which together represent 95% of the mouse brain volume. The decision-making activity, and particularly reward, lit up the brain like a Christmas tree,” said Professor Alexandre Pouget, Co-Founder of IBL and Group Leader at the University of Geneva.
The IBL project began in 2017 with an approach modeled after large-scale collaborations in physics and biology such as CERN and the Human Genome Project. The collaboration uses standardized tools and data processing methods to ensure reproducibility among participating laboratories.
“We’d seen how successful large-scale collaborations in physics had been at tackling questions no single lab could answer, and we wanted to try that same approach in neuroscience. The brain is the most complex structure we know of in the universe and understanding how it drives behavior requires international collaboration on a scale that matches that complexity,” said Professor Tom Mrsic-Flogel, Director of the Sainsbury Wellcome Centre at UCL and one of IBL’s core members.
Using Neuropixels probes for simultaneous neural recordings while mice performed decision-making tasks, researchers observed that signals related to decision-making are distributed throughout many regions rather than being confined to specific areas. This finding challenges traditional models suggesting hierarchical information processing within localized regions.
The study also examined how prior expectations influence perception during challenging trials where cues were faint or ambiguous. It found that expectations are encoded not only in cognitive regions but also within sensory processing areas such as the thalamus.
“The efforts of our collaboration generated fundamental insights about the brain-wide circuits that support complex cognition; this is really exciting and a major step forward relative to the “piecemeal” approach (1-2 brain areas at a time) that was previously the accepted method in the field. Moreover, our team took rigor and reproducibility very seriously. We developed an entire task force that leveraged our unique, multi-lab approach to determine the extent to which our efforts at standardization enhanced reproducibility. My hope going forward is that both our scientific discoveries and our new insights on reproducibility will have an impact in the field,” commented , professor of Neurobiology at the University of California, Los Angeles (UCLA) and one of IBL’s core members.
“Traditionally, neuroscience has looked at brain regions in isolation. Recording the whole brain means we now have an opportunity to understand how all the pieces fit together. This was too big of a project for any one lab, and a collaboration on this scale was only possible because of the dedication and talent of our staff scientists, who are the best in the business,” said Dr Kenneth Harris, Professor of Quantitative Neuroscience at UCL.
Dr Matteo Carandini, Professor of Visual Neuroscience at UCL added: “It’s immensely gratifying to see the IBL deliver the first brain-wide map of neural activity with such high spatial and temporal resolution. The map describes the activity of over 650,000 individual neurons with single-spike resolution. This activity underlies the brain’s sensory and motor activity that constitutes a decision. The map is a fantastic resource that is already being mined by myriad scientists, and yielding unexpected discoveries. It’s a great success for team science and open science.”
Looking ahead, IBL plans to expand its research beyond decision-making into other neuroscience topics while continuing its commitment to open data sharing with global researchers.
“The brain-wide map is undoubtedly an impressive achievement, but it marks a beginning, not the grand finale. The IBL has shown how a global team of scientists can unite, pushing each other beyond comfort zones into uncharted territories no single lab could reach alone. For me, working within the IBL meant constantly confronting the limits of my own knowledge while learning from the extraordinary expertise of colleagues. The IBL has set the highest standards for sharing high-quality data, tools, and resources to accelerate scientific progress. Now, the next horizon is to extend this collective expertise to the entire community. We envision diverse groups of scientists joining IBL to pursue their own projects, leveraging the unique expertise of the IBL staff and benefiting from the open exchange of data and ideas that only large-scale collaboration can offer,” commented Tatiana Engel, Associate Professor at Princeton University.
All data collected from these studies are available online for further analysis by neuroscientists worldwide.
