In his second talk, Kriegstein provides an overview of the use of cerebral organoids to study brain development and disease. Cerebral organoids are models that can be produced from induced pluripotent stem cells. Although organoids can contain the same broad categories of cell types found in the brain, organoids lack the structural, layer-like organization observed in the primary tissue. In addition, the gene expression profile is different between organoids and primary brain tissue. Nevertheless, although organoids do not reproduce all of the features of a developing human cortex, organoids can be a powerful model to study neuronal diseases and evolution, particularly when studying cells that cannot be found in animal models (e.g. oRG cells) or when scientists do not have access to primary brain tissue.