Neurons in early sensory cortices typically respond to simple stimulus features that vary along continuous axes. In vision and hearing, neurons exhibit simple feature tuning, such as selectivity for edges or tones. These basic responses provide the building blocks upon which richer representations are built. In olfaction, however, no such simple feature tuning has been observed, precluding a clear logic for cortical odour coding. I will show that respiration provides the organizing scaffold. Individual piriform neurons are tuned to specific phases of the sniff cycle, and their phase preferences are consistent across inputs. Phase locked ensembles organize population activity along a low dimensional cylindrical manifold, supporting flexible and enriched odour representations. I will also discuss the circuit processes that support this coding scheme. More broadly, these findings identify respiration as an organizing axis of cortical computation and show how rhythmic physiological signals structure neural population dynamics.