In the latest Under the covers (Nature revealed) blog, Nature’s Art Director Kelly Krause discusses the inspiration behind this week’s front cover choice on brain-wide axonal projection patterns.

Caption:

Axonal projection patterns from 21 distinct cortical areas (differentially colour coded) derived from 21 mapping experiments to sample the entire cortex, and rendered in 3D by the Brain Explorer program. In this issue, Hongkui Zeng and colleagues present the first brain-wide, mesoscale connectome for a mammalian species — the laboratory mouse — based on cell-type-specific tracing of axonal projections. The wiring diagram of a complete nervous system has long been available for a small roundworm, but neuronal connectivity data for larger animals has been patchy until now. The new 3D Allen Mouse Brain Connectivity Atlas is a whole-brain connectivity matrix that will provide insights into how brain regions communicate. Much of the data generated in this project will be of relevance to investigations of neural networks in humans.

A 3D wiring diagram for the mouse brain.

From the Art Desk:

Art Director, Kelly Krause, explains:

“I think most people find brain maps to be captivating. It’s probably because we still have so much to discover in this area. This map in particular is a stand-out visualization — it drew our attention immediately.

“It’s obvious that a tremendous amount of work went into the creation of this image.

Hongkui Zeng, one of the authors of the paper, explained to Krause how it was created.

She said: “This image shows the brain-wide axonal projection patterns from 21 distinct cortical areas (differentially color coded). It represents 21 mapping experiments selected from the Allen Mouse Brain Connectivity Atlas to sample the entire cortex. High resolution images from each experiment are quantified and co-registered into a common 3-D reference space using automated methods. Each of the viral tracer injection sites (source regions), which are in the right hemisphere only, is indicated by a cluster of round spheres. The connectivity paths are created by virtual tractography, namely, each sampled target location (squares) is computationally traced through the highest signal density path back to the injection site. The 3-D visualization is generated using the Brain Explorer(r) program.”

For additional behind the scenes commentary each week, check out Nature Graphics Tumblr and the previous Under the Covers on Quantum Cryptography.