New Brain Maps Can Predict Behaviors
Published in Brain Activity, Scanners and Imaging.
Rapid advances in large-scale connectomics are beginning to spotlight the importance of individual variations in the neural circuitry. They also highlight the limitations of “wiring diagrams” alone.
A 3D model of closely bundled pyramidal neurons running through cortical layer 5 of a mammalian brain; the neurons have been colored differently to distinguish them. Researchers have undertaken the construction of “connectomes” that map all the synaptic connections within the brains of several species, including humans.
Olena Shmahalo for Quanta Magazine; source: Daniel Berger and Jeff Lichtman/Lichtman Lab at Harvard University
Last summer a group of Harvard University neuroscientists and Google engineers released the first wiring diagram of a piece of the human brain. The tissue, about the size of a pinhead, had been preserved, stained with heavy metals, cut into 5,000 slices and imaged under an electron microscope. This cubic millimeter of tissue accounts for only one-millionth of the entire human brain. Yet the vast trove of data depicting it comprises 1.4 petabytes’ worth of brightly colored microscopy images of nerve cells, blood vessels and more.
“It is like discovering a new continent,” said Jeff Lichtman of Harvard, the senior author of the paper that presented these results. He described a menagerie of puzzling features that his team had already spotted in the human tissue, including new types of cells never seen in other animals, such as neurons with axons that curl up and spiral atop each other and neurons with two axons instead of one. These findings just scratched the surface: To search the sample completely, he said, would be a task akin to driving every road in North America.