Characterization of perinatally born glutamatergic neurons of the mouse olfactory bulb based on NeuroD6 expression reveals their resistance to sensory deprivation

During postnatal olfactory bulb (OB) neurogenesis, predetermined stem cells residing in the ventricular–subventricular zone continuously generate progenitors that migrate in the rostral migratory stream and integrate into the OB. Although the vast majority of these postnatally generated interneurons are inhibitory, a sub‐fraction represents glutamatergic neurons that integrate into the superficial glomerular layer. In the present work, we demonstrate that the bHLH transcription factor NeuroD6 is specifically and transitorily expressed in the dorsal neurogenic lineage that generates glutamatergic juxtaglomerular cells (JGCs) for the OB. Using lineage tracing combined with whole brain clearing, we provide new insight into timing of generation, morphology, and connectivity of glutamatergic JGCs. Specifically, we show that all glutamatergic JGCs send complex axons with varying projection patterns into different layers of the OB. Moreover, we find that, contrary to GABAergic OB interneurons, glutamatergic JGCs survive under sensory deprivation, indicating that inhibitory and excitatory populations are differentially susceptible to environmental stimulation. NeuroD6 is specifically and transitorily expressed in the dorsal neurogenic lineage that generates glutamatergic juxta‐glomerular neurons for the olfactory bulb. Using NeuroD6‐Cre knock‐in mice as reliable tools, we characterize their morphology and connectivity. Furthermore, by in vivo imaging, we demonstrate that glutamatergic excitatory interneurons survive under sensory deprivation.