Whereas cells regularly renew themselves in most endogenous tissues, the number of nerve cells in the human brain and spinal cord remains constant. Although nerve cells can regenerate in the brains of adult mammals, as LMU scientist Professor Magdalena Götz has previously shown, young neurons in brain injury patients are unable to integrate into existing neural networks and survive, outside of two specific areas of the brain. This appears to be due to glial cells, which form the supporting tissue in the brain. Microglia in particular trigger inflammations and lead to scars that isolate the injured site from the healthy brain, but on the long run prevent proper incorporation of new neurons to the circuitry. How the body regulates such mechanisms was previously unknown.