Being able to see how the brain grows, changes and sometimes malfunctions at the cellular level could help scientists improve their understanding of the many neurological disorders that reduce quality of life for a third of the world's people.

"Much like a detailed GPS for the brain's complex landscape, brain atlases serve as essential reference tools," said Katrin Amunts, a neuroscientist at the Jülich Research Center in Germany, who oversaw Europe's major human brain mapping project, EBRAINS.

Published in the journal Nature, a new set of brain atlases hopes to build on the EBRAINS project. It details how the brain develops in humans and other mammals from the earliest stages of cell division into a rich and diverse assortment of distinct cells that perform specialized functions.

Amunts was not involved in the new research, but told DW the latest brain atlases, including others in development across the world, could lead to better diagnosis techniques for disorders like Alzheimer's or epilepsy. Some atlases could be used to study neurodevelopmental conditions like autism or autoimmune complications like multiple sclerosis.

Other benefits could include "more precise neurosurgery planning, and targeted treatments like Deep Brain Stimulation for Parkinson's Disease," said Amunts in an email.

"By providing a spatial blueprint across species, they help translate research into therapies that could one day improve quality of life for millions."

Multiple maps give a glimpse into our gray matter

What is unique about the new brain atlases is that they show more than single-point snapshots of cells in the brain, but how they change over time.

They are, officially, only draft maps of the brain, but "the insights they provide are groundbreaking," Amunts said.

The atlases are composed of data from human, non-human primates, and mouse studies. In all, 12 studies from research centers in North America, Sweden, Belgium and Singapore form the body of work.

"The idea is to have all these snapshots at different times and you try to link them together to create this map of changes," said Hongkui Zeng, Director of the Allen Institute for Brain Science in the US.

Zeng's research group monitored early gene signatures in developing cells and tracked how these structures change and move in the mouse brain over time to create a "trajectory map."

"Once we have this map, we can take a diseased tissue, and we do the same thing, we profile and we match the cells into the reference atlas and see what has changed," Zeng said.

For example, brain tissue from a deceased person who lived with Alzheimer's Disease, a form of dementia, could be compared to a healthy brain map to understand where and when changes with the disease had occurred.

Challenges to improve brain atlases persist

While human samples are being used to build brain atlases, mouse brain maps are the most comprehensive at the cellular level. This is because researchers have greater difficulty accessing suitable human brain tissue.

Human tissue for scientific use is sourced from so-called brain banks. As with any form of organ donation, brains that are gifted to these repositories require prior consent. Brain donations are less common than the donation of other organs, such as livers or kidneys.

While a difficult subject for many, the lack of brains donated by the families of diseased children also limits the availability of suitable cellular tissue for inclusion in brain atlases.

"All animal work that we do doesn't get close to the human itself. We can extrapolate, we can model, but it's important to [study humans]. We hope to advocate for more willingness of brain donation for research," said Zeng.

Zeng said many of the human samples used in these new brain atlases were sourced from the US and Europe. Brain banks are opening up in other parts of the world, but the current situation indicates that studies may lack diversity.

"We only sample a very narrow portion of human diversity. Human diversity is vast relative to animals," Zeng said.

The researchers hope their studies can be expanded to include populations from Asia and Africa "to really understand how our brains compare with each other at this exquisite cellular level," said Zeng.

Edited by: Zulfikar Abbany