During human ageing and in diseases and injuries affecting the brain and spinal cord, such as stroke and ALS (amyotrophic lateral sclerosis), cells in the brain and spinal cord die, leading to disability. We have found that astrocytes are key to slowing or even reversing this process. When neurons are damaged as a result of disease, astrocytes are activated and focus on minimizing and limiting the damage, especially in the acute phase after a brain injury. However, highly activated astrocytes, which form a scar of cells, can prevent the return of function in the long term by, among other things, inhibiting the formation of new connections between neurons. In transgenic mice, we have now managed to avoid harmful scarring and thus new connections have been formed between the remaining cells. The goal of this project is to pharmacologically control astrocyte activation and thus improve recovery after stroke. In preliminary studies, we have thus been able to slow down the course of the disease in mice with ALS. Increased knowledge of astrocyte activation and pharmacological control of their function offers great opportunities to develop new treatments for stroke and for neurodegenerative diseases.