Many differences in cortical development between human, non-human primate and rodent have been documented, including an expanded SP8 and SG9, expansion of association areas particularly in frontal lobe8, expansion of superficial layers that greatly increase the extent of cortico-cortical connections, and the appearance of a secondary proliferative zone, the SZo, that likely allow the massive expansion of human cortex6,7. We find transcriptional features related to each of these anatomical features, although we were able to identify only minimal molecular differences between the SZi and SZo, leaving open the question of what distinguishes this primate-specific zone of cortical precursors. These data also provide a powerful map to pin an anatomical and developmental locus on genes related to neurodevelopmental disease origins and human-specific brain function and evolution. Although the current analyses only scratch the surface, these data will be extremely useful for generating and testing new hypotheses about molecular substrates for specific features of human brain development and function.
