A cubic millimeter of brain tissue, though seemingly insignificant, packs a powerful punch. Within this tiny space reside 57,000 cells, 230 millimeters of blood vessels, and a staggering 150 million synapses, all contributing to a mind-boggling 1,400 terabytes of data. Researchers from Harvard, led by Professor Jeff Lichtman, and Google have collaborated to achieve a milestone in brain mapping.
Their groundbreaking work, published in Science, unveils the most detailed 3D reconstruction of a human brain segment to date. This piece of temporal cortex, roughly half the size of a rice grain, is depicted with exceptional clarity, showcasing every cell and its intricate web of neural connections.
This nearly decade-long collaboration leverages the expertise of both parties. Lichtman's team utilizes electron microscopy imaging to capture intricate details, while Google's AI algorithms color-code and reconstruct the complex wiring of the mammalian brain.
The ultimate goal, supported by the BRAIN Initiative, is to create a high-resolution map of an entire mouse brain's neural network. This ambitious project would require processing roughly 1,000 times more data than the current human cortex map.
The current map, published in Science, reveals previously unseen aspects of brain structure. These include a rare type of axon with exceptionally strong connections, formed by up to 50 synapses. Additionally, the team observed unusual features like a small number of axons forming intricate loops. Since the sample came from an epilepsy patient, further research is needed to determine if these are pathological or simply uncommon.
Google's advanced AI tools enable the reconstruction and 3D mapping of brain tissue. The team has generously made these tools publicly available, allowing other researchers to examine and annotate the connectome. This commitment to open access ensures that the project's benefits extend beyond the immediate collaborators.
The next frontier for this research team is the mouse hippocampal formation, a region crucial for memory and implicated in neurological disorders.