Experience influences elemental and configural perception of certain binary odour mixtures in newborn rabbits

Abstract

SUMMARYElemental and configural olfactory perception allows interaction with the environment from very early in life. To evaluate how newborn rabbits can extract and respond to information from the highly complex chemical surroundings, and how experience acts on this sensory, cognitive and behavioural capability, we ran a study in four steps including a total of eight experiments. We mainly used a binary AB mixture comprising ethyl isobutyrate (component A) and ethyl maltol (component B), previously shown as a bearer of blending properties; in rabbit pups (as in human adults), the mixture elicits a weak configural perception, i.e. the perception of a configural odour different from the odours of the components. First, a repeated exposure to one component of AB led to a more elemental perception of this mixture; conversely, a repeated exposure to AB facilitated its configural processing. Second, similar impact of experience did not appear with a non-blending AC mixture (ethyl isobutyrate-guaïacol). Third, repeated exposure to AB impacted not only the perception of AB, but also and in the same way the perception of the AC mixture sharing one component, and reciprocally. However, facilitation to perceive one mixture in one mode (configural/elemental) was not generalized to a mixture sharing no components with the experienced mixture [AB versus DE (damascenone and vanillin)]. Thus, experience contributes to the neonatal perception of odour mixtures and adds plasticity to the perceptual system. However, this impact remains dependent on the chemical composition of the mixtures.

Experience shapes our odor perception but depends on the initial perceptual processing of the stimulus

“…This result bolsters the hypothesis that preexposure to A and B components could decrease the configural processing of the AB blending mixture, an effect already observed with a ternary blending mixture in humans , and also in rabbit neonates with the same binary AB mixture (Sinding et al, 2011).…”

“…Conversely, repeated conditioning (nine episodes) to the AB mixture improved its configural perception, because a large percentage of pups responded to the mixture, but only a few responded to the single components (Sinding et al, 2011). Such experience-induced improvements of elemental or configural perception were not observed with an AC mixture, which remained elementally processed by rabbit pups, regardless of their experience with the mixture or its components (Coureaud et al, 2009;Sinding et al, 2011). Overall, these results suggest that experience could modulate the perception of some, but not all, odor mixtures.…”

“…Mixture perception relies on two aspects: the abilities to recognize components within mixtures (elemental perception) and to process mixtures as single odor objects (configural perception; e.g., Coureaud, ThomasDanguin, Wilson, & Ferreira, 2014;Livermore, Hutson, Ngo, Hadjisimos, & Derby, 1997;Rabin, 1988;Sinding, Thomas-Danguin, Crepeaux, Schaal, & Coureaud, 2011). Most animal studies have used conditioning to show the effects of experience on odor mixture perception.…”

“…Indeed, after repeated conditioning to binary or ternary mixtures initially perceived in an elemental manner, tested rats or catfishes no longer generalized the learned information to its single components, suggesting that the mixtures became perceived as configurations (Staubli, Fraser, Faraday, & Lynch, 1987;Valentincic, Kralj, Stenovec, Koce, & Caprio, 2000). In newborn rabbits, it has been shown that repeated conditioning can favor configural processing of the AB mixture (ethyl isobutyrate + ethyl maltol; Sinding et al, 2011) known to elicit the configural perception of a pineapple odor in human adults (Le Berre et al, 2010;Le Berre et al, 2008). Indeed, after a single conditioning to one component of the mixture, 2-dayold rabbit pups selectively responded to that odorant, but they did not respond to the AB mixture.…”

Sensory preconditioning in newborn rabbits: from common to distinct odor memories

“…Therefore, the stronger reinforced associations may have competed with the weaker unreinforced one after conditioning and have consequently induced its rapid forgetting. From an ecological point of view, it may be important for an organism, even a young one, to efficiently learn elements and/or their associations in odor mixtures (Coureaud et al 2008(Coureaud et al , 2009b and to keep in memory only the most relevant associations (for instance, the most recent or the most repeatedly encountered; Sevelinges et al 2009;Sinding et al 2011). Future studies will have to examine this competition assumption.…”