Functional relevance of dual olfactory bulb in olfactory coding

Bilateral convergence of external stimuli is a common feature of vertebrate sensory systems. This convergence of inputs from the bilateral receptive fields allows higher order sensory perception, such as depth perception in the vertebrate visual system and stimulus localization in the auditory system. The functional role of such bilateral convergence in the olfactory system is mostly unknown. To test whether each olfactory bulb contributes a separate piece of olfactory information, and whether information from the bilateral olfactory bulb is integrated, we synchronized the activation of olfactory bulbs with blue light in mice expressing channelrhodopsin in the olfactory sensory neurons and behaviorally assessed the relevance of dual olfactory bulb in olfactory perception. Our findings suggest that each olfactory bulb contributes separate components of olfactory information and mice integrate the olfactory information from each olfactory bulb to identify an olfactory stimulus. Significance statement Identifying an odor is the first step in olfactory coding, as it is critical for the survival of most animals. Previous studies have shown that bilateral olfactory bulbs help rodents to localize the odor source and navigate accordingly. But It is still unclear whether the bilateral olfactory information plays any role in determining odor identity. Here for the first time, using optogenetics and behavioral experiments, we demonstrate that each olfactory bulb provides distinct olfactory information, and rodents integrate information from the two bulbs to identify an odor.