Healthcare (Commonwealth Union) – The Machine Intelligence from Cortical Networks (MICrONS) Project has produced the most comprehensive neural wiring map of a mammalian brain ever created. Today, researchers released the groundbreaking results of this vast dataset in a series of ten papers published in Nature and its affiliated journals. The full connectome and associated data—accessible via the MICrONS Explorer—total 1.6 petabytes (roughly equivalent to 22 years of continuous HD video) and provide unprecedented insights into how the visual cortex functions and is structured.
David A. Markowitz, Ph.D., former IARPA program manager who led the initiative indicated that these breakthroughs from MICrONS, featured in this special issue of Nature, represent a pivotal milestone in the field of neuroscience and its impact could rival that of the Human Genome Project in terms of transforming our understanding of complex biological systems.
He further pointed out that IARPA’s ambitious investment in the MICrONS initiative has broken through past technological barriers, delivering the first-ever platform capable of linking brain structure to function at the scale required to probe the foundations of intelligence. Markowitz indicated that this breakthrough confirms the power of our targeted research strategy and lays the groundwork for future expansion to mapping the entire brain.
Researchers from Baylor College of Medicine and Stanford University initiated the process by utilizing advanced microscopes to monitor the brain activity within a minuscule one cubic millimeter section of a mouse’s visual cortex. This was done while the mouse was exposed to a variety of films and YouTube videos. Following this, experts from the Allen Institute took the identical cubic millimeter of brain tissue and meticulously divided it into over 25,000 slices, each incredibly thin at just 1/400th the diameter of a human hair. These slices were then subjected to high-resolution imaging using a series of electron microscopes. Concluding the study, a separate team at Princeton University employed artificial intelligence (AI) and machine learning technologies to recreate the cells and their interconnections in a three-dimensional space. This comprehensive approach, paired with the data on brain activity, has resulted in the most extensive and detailed wiring diagram and functional map of the brain ever created. It encompasses over 200,000 cells, an impressive four kilometers of axons – the extensions that facilitate communication with other cells, and a staggering 523 million synapses – the junctions where cells connect.
“Inside that tiny speck is an entire architecture like an exquisite forest,” explained Clay Reid, M.D., Ph.D., senior investigator and one of the early founders of electron microscopy connectomics who was responsible for bringing this area of science to the Allen Institute 13 years back. “It has all sorts of rules of connections that we knew from various parts of neuroscience, and within the reconstruction itself, we can test the old theories and hope to find new things that no one has ever seen before.”
The studies unveiled a host of breakthroughs, including newly identified cell types, novel traits, and fresh insights into how the brain is organized and functions. One of the most striking discoveries was a previously unknown principle of inhibition in the brain. While inhibitory neurons were long believed to act as blunt instruments—dampening activity across the board—scientists found they actually operate with remarkable precision. These cells selectively target specific excitatory neurons, orchestrating a complex network of communication and control. Some work in coordination to suppress broad neural activity, while others act with surgical accuracy, fine-tuning the behavior of individual cell types.
“This is the future in many ways,” said Andreas Tolias, Ph.D., who is a lead scientists who was engaged in the project at both Baylor College of Medicine and Stanford University.
