Being superficial: a developmental viewpoint on cortical layer 1 wiring

Functioning of the neocortex relies on a complex architecture circuits, as illustrated by causal link between neocortical excitation/inhibition imbalance and etiology several neurodevelopmental disorders. An important entry point to cortical circuits is located in superficial layer 1 (L1), which contains mostly local long-range inputs sparse inhibitory interneurons that collectively regulate cerebral functions. While increasing evidence indicates L1 has physiological roles, our understanding how it wires up during development remains limited. Here, we provide an integrated overview anatomy, function development, with focus transient early born Cajal-Retzius neurons, highlight open questions key for progressing this essential yet understudied cortex.