Timing Matters: Lessons from Perinatal Neurogenesis in the Olfactory Bulb
In the olfactory bulb odorant receptor specific input converges into glomeruli. Deep to the glomeruli coding of odor information is tuned by local synaptic circuits. Deciphering the dendritic organization of granule cells relative to the secondary dendrites of projection neurons is a pivotal for understanding odor processing. We carried out a detailed interrogation of the granule cells including the timing of neurogenesis, laminar distribution and synaptogenesis between granule cells and projection neurons. In brief, the granule cells develop following a outside in maturation pattern from embryogenesis to adulthood following a developmental continuum. Granule cells born one week after birth exhibit a unique sublayer specific distribution pattern, marking a transition between embryonic or neonatal and adult stages. Integration into reciprocal synaptic circuits occurred 10 days post neurogenesis, We conclude that timing of neurogenesis dictates the anatomical configuration of granule cells within the olfactory bulb, which in turn regulates a preferential synaptic integration with either mitral cell or tufted cell secondary dendrites. Summary StatementThe integration and distribution of granule cells into the olfactory bulb is determined by the timing of neurogenesis. Location of somata shifts from superficial to deep during development.