Timing of neurogenesis is a determinant of olfactory circuitry

An odorant receptor map in mammals, that is constructed by the glomerular coalescence of sensory neuron axons in the olfactory bulb, is essential for proper odor information processing. However, how this map is linked with olfactory cortex is unknown. Here, we use a battery of methods, including various markers of cell division in combination with tracers of neuronal connections and time-lapse live imaging, to show that early- and late-generated mouse mitral cells become differentially distributed within the dorsal and ventral subdivisions of the odorant receptor map. In addition, we demonstrate that the late-generated mitral cells extend significantly stronger projections to the olfactory tubercle than the early-generated. Together, these data indicate that the odorant receptor map is developmentally linked to the olfactory cortices in part by the birthdate of mitral cells. This endows different olfactory cortical regions a role to process information from distinct regions of odorant receptor map.