As part of President Obama’s BRAIN Initiative–a project intended to accelerate our understanding of the brain–researchers have diagrammed a connectome of the mouse brain for the first time ever. The connectome shows how the mouse brain is wired and how the neurons of the brain connect to one another to communicate..
The image below is an overall view of the mouse brain connectome:
And this circular wiring diagram shows the connections among 215 distinct regions of the brain, with connections from 11 cortical regions shown in colors and the others shown in gray:
Mapping the connectome revealed some interesting findings. For example, the researchers found that connections that remain on one side of the brain are stronger than those that travel across the hemispheres. As well, they found that the connections between the neurons vary greatly in strength.Prior to this, the only connectome that scientists have successfully and completely mapped is for the roundworm – which only has around 300 neurons. The mouse brain contains about 75 million neurons, and the human brain, around 85 billion.
The mouse connectome project was led by Hongkui Zeng of the Allen Institute for Brain Science in Seattle. Of the nearly 300 structures in the mouse brain, the researchers were able to map the connections between all but 18 structures, mostly the ones that are very tiny and located at the bottom of the brain.
For more photos and details on this project, you can view the abstract at Nature Neuroscience.