As we age, the brain undergoes changes that lead to various disorders that affect physical ability and mental acuity. There are many processes at play, ranging from alterations in the extracellular environment, to accumulation of deleterious proteins, to a breakdown in connections between neurons. Can these processes be reversed?  Dr. Jean Herbert from the Albert Einstein School of Medicine has led efforts to reconstitute brain function through use of stem cells. Current steps in animal models may one day contribute to human therapies.