The brain undergoes dramatic change during the first years of life. Its circuits readily rewire as an infant and then child encounters new sights and sounds, taking in the world and learning to understand it. As the child matures and key developmental periods pass, the brain becomes less malleable—but certain experiences create opportunities for parts of the adult brain to rewire and learn again.
source https://www.lifetechnology.com/blogs/life-technology-medical-news/research-team-investigates-abnormal-neuron-activity-in-rett-syndrome