SPLTRAK Abstract Submission
The logic of olfactory bulb outputs revealed by high-throughput single-neuron projection mapping using sequencing
Yushu Chen, Xiaoyin Chen, Justus M. Kebschull, Alexei Koulakov, Anthony M. Zador, Dinu F. Albeanu
Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States

The olfactory bulb relays information about odor objects represented by olfactory sensory neurons through its output neurons, the mitral and tufted (M/T) cells, to higher brain areas. These areas have been proposed to perform distinct functions ranging from odor detection and localization, guiding spatial navigation to odor identification and innate, or learned, stimulus value assignment. Understanding the logic of information flow from the bulb to the rest of the brain is crucial for unraveling the computations performed by olfactory circuits. Current state-of-the-art microscopy-based neuroanatomy is limited in throughput, and therefore difficult to scale up for robust statistical analysis of neuronal projections at cellular resolution. Using MAPseq, a novel high-throughput method for mapping single-neuron projections via barcode sequencing, we investigated the single-cell projection patterns of 1,466 mitral and tufted cells (3 mice). Our data recapitulates the distinct, but distributed projection patterns of M/T cells previously observed using single-neuron tracing. Furthermore, we identified structured modules of projections from mitral cells to distinct domains along the anterior-posterior axis of the piriform cortex. These modular structures contained well-defined collaterals to non-piriform areas, and were reproducible across animals. Our results indicate that information flows from the bulb to higher brain areas in a structured, non-random fashion. Currently, we further examine the spatial distribution of mitral and tufted cells with specific projection modules using a combination of laser capture microdissection and in situ barcode sequencing.