Scientists in Sydney have discovered a way to stimulate the brain's own stem cells, which has the potential to lead to a new treatment for neurological disorders such as Parkinson's and Alzheimer's disease.

Bryce Vissel and Andrea Abdipranoto at the Garvan Institute of Medical Research identified a chemical, called activin A, that is essential for the brain's own stem cells to form new nerve cells, and to repair the brain, following neurodegeneration.

Using a mouse model, the researchers showed that, following acute nerve cell damage, the brain immediately acts to repair itself by replacing the damaged nerve cells with new cells.

The researchers then showed that the brain does this by releasing activin A. But when the chemical was blocked, regeneration stopped.

After five years of laboratory testing, the researchers made the surprising finding that activin A has an essential but indirect role in regeneration: it works by inhibiting the replication and activation of inflammatory cells.