Immature olfactory sensory neurons provide complementary input in the healthy olfactory system

Adult neurogenesis of olfactory sensory neurons (OSNs) provides the unique opportunity to understand how new neurons functionally integrate into existing circuitry and contribute to behaviors. Previous studies have shown that immature OSNs express odorant receptors, form dendritic knobs with short cilia, and project their axons into the olfactory bulb (OB) to form functional synapses. Furthermore, a previous study found that immature OSNs respond selectively to odorants and exhibit graded responses in a higher odorant concentration range than mature OSNs. Finally, this study also showed that, in mice that lack mature OSNs, sensory input from immature OSNs can mediate odor detection and discrimination. What remains unknown is how these immature OSNs contribute to odor-guided behavior in the healthy, intact olfactory system. Here we show that chemogenetically silencing immature OSNs impairs odor detection ability in a buried food assay. Furthermore, immature OSN silencing reduces the amplitude of odor-evoked dendritic calcium responses in OB neurons in vivo . Together, these findings suggest that immature OSNs provide distinct odor input that complements mature OSN input to contribute to odor-guided behaviors in the healthy, intact olfactory system.