The ability to consistently recognise an object despite variable sensory input is termed perceptual constancy. This ability is not innate, rather it develops early in life yet little is known about the neural processes underpinning its development. 

We have taken advantage of the olfactory system of mice and using behavioural tests show that, when mice are naïve to an odour, perceptual constancy is not maintained for an odour across increasing concentration (n = 32). 2-photon imaging of neural activity in the olfactory bulb revealed that the perceptual change coincides with a rapid reduction in activity in a single glomerulus that is most sensitive to the odour (n = 9).  This drop in activity is not a property of circuit interactions within the olfactory bulb; it is already present in the olfactory sensory neurons (n = 13). Computational modelling shows that the rapid adaptation at higher concentrations is due to a sensitivity mismatch of olfactory receptor neurons resulting in transmission failure from the nose. 

We then show that upon forming an association of this odour with food, mice perceive the odour as the same object across the whole range of concentrations tested (n = 7). Correspondingly the sensitive glomerulus no longer displays rapid adaptation, due to a large sensitivity shift that matches its dynamic range to that of the food odour, when transmission failure is prevented, perceptual constancy is maintained. This work shows that the plasticity of the primary sensory organ enables learning of perceptual constancy.