Japan’s Fugaku Supercomputer Powers the Most Realistic Virtual Brain Ever

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A New Milestone in Digital Neuroscience

Scientists have taken a major leap toward understanding the brain by building one of the most detailed virtual mouse cortices ever simulated. By merging massive biological datasets with the extraordinary computational power of Japan’s Fugaku supercomputer, researchers created a digital brain that behaves strikingly like a living system. This simulation includes millions of neurons and tens of billions of synapses, allowing scientists to observe brain activity at resolutions once thought impossible.

The virtual cortex offers unprecedented opportunities: researchers can now watch how disorders such as Alzheimer’s disease or epilepsy emerge, how damage spreads across neural circuits, and how complex brain rhythms contribute to attention and cognition.

Powered by Fugaku — One of the Fastest Machines on Earth

Fugaku, developed by RIKEN and Fujitsu, is among the fastest supercomputers ever built. Capable of more than 400 quadrillion operations per second, its processing power enabled a simulation with nearly ten million neurons, 26 billion synapses, and 86 interconnected brain regions. Such an undertaking would be impossible with traditional computing systems.

Its design reflects this scale: more than 158,000 computing nodes work together to process staggering volumes of biological and mathematical data. Named after Mount Fuji, Fugaku symbolizes both towering performance and broad scientific reach—from climate science to medical research, and now, highly detailed neural modeling.

Building a Living Digital Cortex

To create the simulation, researchers transformed extensive biological datasets—such as those from the Allen Cell Types Database and the Allen Connectivity Atlas—into a functional digital model. Using the Brain Modeling ToolKit, biological measurements were converted into computational frameworks. Another tool, Neulite, translated complex mathematical equations into virtual neurons capable of firing, signaling, and interacting in real time.

The result is a simulation that does more than represent brain structure—it behaves like a living cortex. It recreates microscopic electrical patterns, realistic neuron morphologies, and spontaneous activity similar to what happens inside an actual resting mouse brain.

As one of the project scientists expressed, “This shows the door is open… much larger models are not only possible, but achievable with precision and scale.”

A Platform for Understanding Disease and Testing Ideas

In traditional neuroscience, studying disorders like epilepsy or Alzheimer’s demands lengthy experiments on real tissue. Now, the virtual cortex offers a powerful alternative: a digital space where scientists can observe early hints of disease, test theories about neural dysfunction, and explore treatments without physical limitations.

Researchers can watch how seizures move across the cortex, how brain waves form and shift, or how early damage in a degenerative disease spreads through neural networks. The simulation provides a safe and controllable environment—one where countless hypotheses can be explored rapidly.

Toward Whole-Brain Digital Models

Although this achievement is extraordinary, the team sees it only as a beginning. Their long-term ambition is to build entire virtual brains, eventually reaching even human-scale models enriched with detailed biological features. With systems like Fugaku, the idea of constructing a fully functional digital brain is shifting from imagination to engineering reality.

This project was made possible through collaboration between the Allen Institute, Japan’s University of Electro-Communications, and several additional Japanese institutions, supported by a multidisciplinary team spanning fields from computational neuroscience to advanced engineering.

Conclusion: A Transformative Step Toward the Future of Brain Science

The virtual mouse cortex marks a new era in neuroscience—one where understanding the brain no longer relies solely on dissecting real tissue but also on building complete, digital counterparts that reveal the hidden dynamics of thought, memory, and disease. With tools like Fugaku and the ambitious vision of international research teams, the dream of constructing whole-brain models is rapidly taking form.

This breakthrough is not just a scientific achievement; it is an invitation to reimagine how we study the mind. As computing power grows and biological data becomes richer, virtual brains may help us uncover the origins of neurological disorders, inspire new treatments, and ultimately deepen our understanding of what makes us human.

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