Humans and mice express similar olfactory preferences

Abstract

In humans, the pleasantness of odors is a major contributor to social relationships and food intake. Smells evoke attraction and repulsion responses, reflecting the hedonic value of the odorant. While olfactory preferences are known to be strongly modulated by experience and learning, it has been recently suggested that, in humans, the pleasantness of odors may be partly explained by the physicochemical properties of the odorant molecules themselves. If odor hedonic value is indeed predetermined by odorant structure, then it could be hypothesized that other species will show similar odor preferences to humans. Combining behavioral and psychophysical approaches, we here show that odorants rated as pleasant by humans were also those which, behaviorally, mice investigated longer and human subjects sniffed longer, thereby revealing for the first time a component of olfactory hedonic perception conserved across species. Consistent with this, we further show that odor pleasantness rating in humans and investigation time in mice were both correlated with the physicochemical properties of the molecules, suggesting that olfactory preferences are indeed partly engraved in the physicochemical structure of the odorant. That odor preferences are shared between mammal species and are guided by physicochemical features of odorant stimuli strengthens the view that odor preference is partially predetermined. These findings open up new perspectives for the study of the neural mechanisms of hedonic perception.

Figure 1. Mice and humans express similar odor preferences.

A. In experiment 1, a significant and positive correlation was found between odor investigation time in mice and odor hedonic rating in humans. B. In experiment 2, using different odorants, a significant positive correlation was also observed between odor investigation time in mice and odor hedonic rating in humans.

Figure 2. Mouse and human odor preferences are driven by odorant structure.

Physicochemical PC1 correlated positively with investigation time in mice (A) and with hedonic rating in humans (B), indicating that hedonic behavior in both species may be driven in part by the physicochemical properties of the molecules.

Figure 3. Two groups of odorants with different physicochemical properties evoke distinct behaviors in mice and humans.

A. Physicochemical PC1 significantly differed for the two sets of odorants. B. Mice investigated odorants longer in experiment 2 than in experiment 1 C. Humans sniffed odorants longer in experiment 2 than in experiment 1 D. Humans preferred the odorants of experiment 2 to those of experiment 1. (t-test, *: p<.05, **: p<.001, ***: p<.0001)