A cell map of parts of the axolotl's brain has yielded further clues to the amphibian's special ability to regenerate. According to a study, eight weeks after an injury to the forebrain, which is also responsible for processing smells, all of the lost nerve cells had been replaced. In part, they had rebuilt their old connections to neighboring cells, said the co-author of the study published in the journal Science, Katharina Lust from the Vienna Research Institute of Molecular Pathology (IMP). "We don't yet know whether the restored neural network will actually work as before," said Lust.

This is how the researchers did it

Led by Elly Tanaka (IMP) and Barbara Treutlein from ETH Zurich, the researchers mapped cell types in the axolotl forebrain and characterized the cells that give the newt its extraordinary ability to regenerate. They also compared the cells with those of turtles and mice. In the evolutionary tree, amphibians split off from the rest of the vertebrates about 350 million years ago. It was not previously known how similar the axolotl brain is to other vertebrate brains.

The researchers also identified clusters of neurons in the axolotl brain that correspond to the mouse and turtle hippocampus, a region responsible for memory and learning. "Mapping cell types in the axolotl brain not only brings evolutionary insight into the vertebrate brain, but also paves the way for innovative research into brain regeneration," said Tanaka.

This is why the axolotl is so popular with researchers

The aim is to understand what brain stem cells do after an injury - which genes they activate, how they interact and how they restore neurons that reconnect the lost connections. "How does each cell 'know' what to do?" says Lust.

The axolotl is a popular subject of research because of its ability to replace even limbs, such as legs.