We are interested in revealing how the brain processes complex odorous stimuli to guide behavior. Many mammalian species rely on the sense of smell for daily basic functions such as finding food, choosing mates, and avoiding predators. In natural settings, odors emitted by these objects will mix with odors emitted from other objects in the environment, prior to reaching the nose. The brain must segment the mixed inputs to be able to detect and identify odors that are behaviorally important. We combine behavioral, electrophysiological, and computational methodologies to reveal the underlying neuronal processes that support the brain’s ability to segment mixtures. We develop behavioral tasks for rodents, that mimic the richness of natural settings, while allowing quantitative analysis, and combine these with dense electrophysiological recordings.

Target-odor detection against background task. Mice are trained to report if a mixture includes a specific target odorant. Trial difficulty is correlated with the glomerular overlap between the target and background odorants.

Similarly to other sensory systems, olfactory brain regions are heavily interconnected via feedforward and feedback connections. While the wiring logic of the feedforward connections has been largely worked-out, that of the feedback connections remains unknown. A major effort in the lab is devoted to understanding the roles played by feedback connections in processing rich and complex odorous stimuli. In addition to electrophysiology during behavior, we also utilize tracing methods and in-vitro preparations to analyze feedback circuit connectivity.

Wiring in the olfactory system. Sensory neurons in the olfactory epithelium express a single olfactory receptor gene (out of ~1300 in the mouse). The projections of sensory neurons expressing the same gene converge in the olfactory bulb to form glomeruli. Mitral and tufted cells, the principal neurons of the olfactory bulb receive inputs from a single glomerulus and therefore represent information from a single receptor type. the olfactory cortex is the first brain station where individual neurons receive converging inputs representing multiple receptor types. The topology of the feedback connections is not yet clear.