Overlap between orthonasal and retronasal response patterns. A: Glomerular activity patterns of 5 different odorants presented orthonasally or retronasally in the same animal. Eugenol (50% v/v for both stimulation modes), methyl isoeugenol (50% v/v for both), valeric acid (50% v/v for both), hexanal (0.1% v/v for orthonasal, 10% v/v for retronasal), methyl benzoate (50% v/v for both) were used for spH imaging. Orthonasal stimuli were delivered for 10 s at 150 ml/min. Retronasal stimuli were delivered for 30 s at 300 ml/min. Response maps for each stimulus mode are rendered in different colors (orthonasal: red, retronasal: green). Scale bar = 200 μm. B: Overlay of orthonasal and retronasal representations expressed in different color channels to indicate the glomeruli responding to one or both airflow pathways (orthonasal only: red; retronasal only: green; both: yellow).