Clonal origins of neocortical interneurons

•Neocortical interneurons are produced as spatially organized clonal units in MGE.•Clonally related interneurons form spatially isolated clusters in mature neocortex.•Individual clonal clusters can contain more than one interneuron subtype.•Progenitor division modes may influence interneuron diversity and distribution.

Once referred to as 'short-axon' neurons by Cajal, GABA (gamma-amino butyric acid)-ergic interneurons are essential components of the neocortex. They are distributed throughout the cortical laminae and are responsible for shaping circuit output through a rich array of inhibitory mechanisms. Numerous fate-mapping and transplantation studies have examined the embryonic origins of the diversity of interneurons that are defined along various parameters such as morphology, neurochemical marker expression and physiological properties, and have been extensively reviewed elsewhere. Here, we focus on discussing two recent studies that have, for the first time, examined the production and organization of neocortical interneurons originated from individual progenitors, that is, with clonal resolution, and provided important new insights into the cellular processes underlying the development of inhibitory interneurons in the neocortex.