Dynamic intraglomerular neuronal ensembles represent odor identity and concentration

The olfactory system has been extensively studied from an anatomical and functional point of view, yet how and where certain basic odor characteristics such as identity and concentration are represented in the brain remains poorly understood. The glomerular layer of the olfactory bulb is the first brain region that integrates olfactory signals and enables a topographic representation of odor identity. We investigated this odor encoding at the intraglomerular network level using genetic labeling, in vivo imaging, and computational methods. Our analyses demonstrated that glomerular glutamatergic neurons encode both odor identity and concentration. Furthermore, in vivo structural and functional imaging of sister neurons revealed the emergence of intraglomerular neuronal ensembles governed by odor identity and concentration. These findings revealed a novel network mechanism that enables the simultaneous coding of odor identity and concentration within glomerular modules, suggesting a potential mechanism for odor decorrelation and a new model for odor information processing in the olfactory bulb. One-sentence summary Unraveling the scent puzzle: Discovery of intraglomerular neuronal ensembles sheds light on odor representation in the brain.