Odorant Response Properties of Individual Neurons in an Olfactory Glomerular Module

SummaryNeuronal networks that are directly associated with glomeruli in the olfactory bulb are thought to comprise functional modules. However, this has not yet been experimentally proven. In this study, we explored the anatomical and functional architecture of glomerular modules using in vivo two-photon calcium imaging. Surprisingly, the deep portions of the glomerular modules showed considerable spatial overlap with other modules. Juxtaglomerular cells showed similar excitatory odorant response profiles to presynaptic olfactory sensory neuron inputs. Mitral cells exhibited a more sharply tuned molecular receptive range compared to juxtaglomerular cells, and their odorant response profiles varied depending on their interneuronal horizontal distances. These data suggest that glomerular modules are composed of functionally distinct neurons, and that homogenous odor inputs to each glomerulus may be parsed and processed in different fashions within the modules before being sent to higher olfactory centers.

► The deep portions of a glomerular module considerably overlap with other modules
► Mitral cells are more narrowly tuned than juxtaglomerular cells
► Adjacent mitral cells from the same glomerulus show similar odorant selectivity
► The selectivity of distant mitral cells from the same glomerulus is less similar