Decoding the olfactory map: targeted transcriptomics link olfactory receptors to glomeruli

The external world is perceived via sensory receptors arranged in highly organized systems according to functional strategies, which in turn reflect features of critical importance to both the sense and the animal. The receptor organization and functional strategies of visual, auditory, and touch sensory systems have been mapped, but such a map for olfaction, the sense of smell, has remained elusive despite a concrete understanding of the fundamental principles of the system’s architecture.Sensory processing in olfactory systems is organized across olfactory bulb glomeruli, wherein axons of peripheral sensory neurons expressing the same olfactory receptor co-terminate to transmit receptor-specific activity to central neurons. Understanding how receptors map to glomeruli is therefore critical to understanding olfaction. High-throughput spatial transcriptomics is a rapidly advancing field, but low-abundance olfactory receptor expression within glomeruli has previously precluded high-throughput mapping of receptors to glomeruli. In Chapter 2, I describe the development and application of a novel method which combines sequential sectioning along the anteroposterior, dorsoventral, and mediolateral axes with target capture enrichment sequencing to overcome low-abundance target expression. This strategy spatially mapped 86% of olfactory receptors across the olfactory bulb and uncovered a relationship between olfactory receptor sequence and glomerular position.