A team of scientists has created a comprehensive circuit diagram of neurons in a mammalian brain’s visual cortex, revealing groundbreaking insights into how the brain works. The map, which covers an area smaller than a grain of sand, documents 84,000 neurons linked by half a billion synapses and approximately 5.4km of neuronal wiring.
The 3D reconstruction of this tiny region, called the cubic millimetre, is helping researchers understand how different cell types work together and potentially shed light on brain disorders such as Alzheimer’s, Parkinson’s, autism, and schizophrenia. The advancements have significant implications for neuroscience, comparable to the Human Genome Project in transformative potential.
Researchers used advanced microscopes to record brain activity while mice watched movies and YouTube clips, then sliced the brain into thin layers using electron microscopes. A third team at Princeton University applied artificial intelligence and machine learning to reconstruct the cells and connections into a 3D volume. The massive data set is equivalent to 22 years of non-stop HD video.
The findings reveal new cell types and a new principle of inhibition within the brain, challenging previous assumptions about inhibitory cells’ role in neural communication. This breakthrough could pave the way for better understanding of brain disorders by providing a “circuit diagram” or blueprint of the brain’s wiring.
Source: https://www.theguardian.com/science/2025/apr/09/us-scientists-create-most-comprehensive-circuit-diagram-of-mammalian-brain