Scientists chart mouse brain neurons in decision-making, unlocking 'mind map' possibilities

Breakthrough in Brain Research: Mapping Neurons During Decision-Making

Scientists have made a groundbreaking achievement by successfully mapping the brain neurons that activate when mice make decisions. This marks the first large-scale recording of individual neuron activity across the entire mouse brain. Researchers believe this could be the initial step toward creating a "map of the mind" that can read thoughts. Could we one day see into the mind, as often depicted in science fiction films?

Ultra-Fine Electrodes and Mouse Experiments

The International Brain Laboratory (IBL) Consortium, which includes 12 universities and research institutions from the U.S. and Europe—such as Stanford University and the Max Planck Institute—recently published a “brain-wide neural activity map” in the journal Nature. This was based on experiments involving 139 mice. The team implanted ultra-fine electrodes into the brains of these mice to record signals from neurons activated during decision-making.

In the experiment, mice were rewarded with water when they turned a steering wheel to move a dot on a screen to the center. If they failed, they received a warning sound and had to wait for a penalty. This setup resembles scenes from the film Stuart Little, where the character drives a toy car by turning a steering wheel.

Through this process, the researchers visualized how neurons in different brain regions turned signals on and off when the mice made decisions. The resulting brain activity map resembled a "light map," similar to satellite images of the Korean Peninsula under night lighting. The team classified 621,700 neuron signal bundles, using 75,000 single-neuron signals for analysis.

The results showed that stimulus signals initially appeared strongly in the visual area, then spread to parts of the midbrain and hindbrain. The choice of direction and reward-related responses were observed across the entire brain, suggesting that decision-making involves a distributed network rather than being limited to specific regions.

Clues to Alzheimer’s Onset?

In April, the U.S. research project "MICrONS Consortium" published a high-resolution connectome (neuron connection map) of a 1 cubic millimeter section of the mouse visual cortex in Nature. This "functional connectome" involved slicing thin brain sections, capturing them with an electron microscope, and reconstructing them in 3D using artificial intelligence (AI). This allowed scientists to compare structure (wiring) and function (response) on the same coordinates, much like a circuit diagram in electronics.

Now, brain scientists have two key maps: the connectome and the brain-wide neural activity map. Perfecting both could allow tracking the path from stimulus to decision at the neuron level and uncover clues about the onset circuits of diseases such as Alzheimer’s and Parkinson’s.

However, the current neural activity map is based on sampling some neurons, and the connectome covers less than 1% of the entire brain. While there is still a long way to go, the intersection of standardized brain neural activity maps and high-resolution connectomes is expected to accelerate research progress toward a "map of the mind."

Understanding the Connectome

A connectome is a map of how neurons in the brain are connected, similar to a circuit diagram in electronics. It represents the mapping of connections (connect) of all (ome) neurons. Creating a connectome involves slicing a deceased brain into thin sections, taking ultra-precise photos, and manually identifying the connection patterns of neurons visible in those images.