TY - JOUR T1 - Mosaic representations of odors in the input and output layers of the mouse olfactory bulb JF - bioRxiv DO - 10.1101/259945 SP - 259945 AU - Honggoo Chae AU - Daniel Kepple AU - Walter G. Bast AU - Venkatesh N. Murthy AU - Alexei Koulakov AU - Dinu F. Albeanu Y1 - 2018/01/01 UR - http://biorxiv.org/content/early/2018/02/05/259945.1.abstract N2 - The elementary stimulus features encoded by the olfactory system remain poorly understood. We examined the relationship between 1,666 physical-chemical descriptors of odors and the activity of olfactory bulb inputs as well as outputs in awake mice. Glomerular and M/T cell responses were sparse and locally heterogeneous, with only a coarse dependence of glomerular positions on physical-chemical properties. Odor features represented by ensembles of M/T cells were overlapping, but distinct from those represented in glomeruli, consistent with extensive interplay between feedforward and feedback inputs to the bulb. This reformatting was well-described as a rotation in odor space. The descriptors accounted for a small fraction in response variance, and the similarity of odors in physical-chemical space was a poor predictor of similarity in neuronal representations. Our results suggest that commonly used physical-chemical properties are not systematically represented in bulbar activity and encourage further search for better descriptors of odor space. ER -