Constructing human neural circuits in living systems by transplantation

Our understanding of how the brain assembles its circuits and how this goes awry in disease remains incomplete. There has been great progress in generating human neurons from stem cells in vitro and, more recently, in constructing circuits with human cells in vivo by transplantation. Here, I highlight approaches, promises, and challenges of growing human neurons in living animals to study human development and disease. Our understanding of how the brain assembles its circuits and how this goes awry in disease remains incomplete. There has been great progress in generating human neurons from stem cells in vitro and, more recently, in constructing circuits with human cells in vivo by transplantation. Here, I highlight approaches, promises, and challenges of growing human neurons in living animals to study human development and disease.