Book excerpt: The development of the young brain after birth and the emergence of cognitive capacities, mind, and individuality rest on the maturation of a dense net of synaptic connections between neurons. Memory Makes the Brain describes the dramatic, competitive elimination of surplus synapses that occur in the young, maturing brain -- in a process called synaptic pruning that was discovered by pediatric neurologist Peter Huttenlocher in the 1970's at the University of Chicago. Explaining similarities between developmental pruning and learning processes in the adult brain, neurobiologist Christian Hansel offers a unique perspective on brain adaptation and plasticity throughout lifetime, at times weaving in personal accounts and memories. The cellular plasticity machinery that enables learning is known to be affected in brain developmental disorders such as autism. Memory Makes the Brain explains how both maturation and adult synaptic plasticity are deregulated in autism, and how we begin to trace back autism-typical behavioral abnormalities to such synaptopathies.