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

Kat Arney

Writer

Dr Kat Arney is an award-winning science writer, broadcaster and public speaker, and is the founder and Creative Director of First Create The Media.

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• Image adapted from work by Alexander Shapson-Coe and Michał Januszewski, and colleagues
• Dept. of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, MA and Google Research, Mountain View, CA, USA
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY-ND-NC 4.0)
• Published in bioRxiv, June 2021 (not peer reviewed)