Defective cortical development is responsible for neurodevelopmental disorders that manifest in childhood and adolescence. However, model systems that can explore the effects of genetic and environmental factors on human cortical development are not well established. Therefore, we developed a novel neurosphere assay that combined recent progress in induced pluripotent stem cell (iPSC) differentiation with advanced live cell imaging techniques to study key aspects of human cortical development. We subsequently applied this assay to investigate the effects of viral infection on cortical development given its established link to neurodevelopmental disorders. We found that viral infection substantially restricted both radial glia growth and neural cell migration. These findings provide new insight into how infections exert deleterious effects on the developing cortex and thus carry important implications for future disease prevention strategies.