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Millions and Millions

Information on brain cell connections in unprecedented detail

28 July 2021

Millions and Millions

Scientists first described the basic structures of the brain back in the first century CE, yet they could only speculate on how it worked. We now know that there are roughly 100 billion cells in a typical human brain, wired together in incredibly complex patterns. Thanks to advances in high-powered microscopy, today’s researchers are now able to see individual brain cells and trace the connections between them in unprecedented detail. These images show different types of information about the three-dimensional structure of 50,000 nerve cells and 133.7 million connections in a single cubic millimetre of human brain tissue: all cells (top left), two different types of nerve cells (top right and bottom left) and supporting cells known as glia (bottom right). While we know more than the early anatomists, understanding how all this complexity generates thoughts and actions is still one of the biggest remaining challenges in biomedical science today.

Written by Kat Arney

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BPoD stands for Biomedical Picture of the Day. Managed by the MRC Laboratory of Medical Sciences until Jul 2023, it is now run independently by a dedicated team of scientists and writers. The website aims to engage everyone, young and old, in the wonders of biology, and its influence on medicine. The ever-growing archive of more than 4000 research images documents over a decade of progress. Explore the collection and see what you discover. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.

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