Brain cells called astrocytes have unexpected role in brain 'plasticity': Researchers show protein made by astrocytes enables the brain's maturation and regulates its flexibility -- ScienceDaily
The signal turned out to be a protein astrocytes secrete called Chrdl1, which increases the number and maturity of connections between nerve cells, enabling the stabilization of neural connections and circuits once they finish developing.
To further understand the role of Chrdl1, the team developed mouse models with the gene disabled by introduced mutations. These mice had a level of plasticity in their brains that was much higher than normal. Adult mice with the Chrdl1 mutation had brain plasticity that looked very much like that of young mice, whose brains are still in early stages of development.