What observer rats don’t learn about foods from demonstrator rats

Does demonstrator relevance affect social preferences and the social transmission of food preferences in female mice (Mus musculus)?

This study examined whether a history of beneficial social learning experiences affects social partner preferences in laboratory mice (Mus musculus) and whether observer mice acquire adaptive model-based social learning strategies through associative learning. We tested whether observers would come to socially prefer demonstrators who provide beneficial information through the social transmission of food preference (STFP), over demonstrators who do not; and whether they would preferentially attend to and learn from such demonstrators. Observers were given repeated exposures to two demonstrators who differed in whether or not they consistently provided beneficial information (which increased observers' ingestion of food via the STFP). After multiple social learning experiences with a "relevant demonstrator" (our CS+) whose demonstrated food was available for consumption (our US) by the observer and a "non-relevant demonstrator" whose demonstrated food was never encountered, neither demonstrator was preferred over the other. Furthermore, observers learned equally well from both relevant and non-relevant demonstrators. The present findings suggest that adaptive model-based social learning strategies are not followed in the STFP, although we recommend further testing of the social preference hypothesis.

Early maternal care predicts reliance on social learning about food in adult rats

Many vertebrates rely extensively on social information, but the value of information produced by other individuals will vary across contexts and habitats. Social learning may thus be optimized by the use of developmental or current cues to determine its likely value. Here, we show that a developmental cue, early maternal care, correlates with social learning propensities in adult rodents. The maternal behavior of rats Rattus norvegicus with their litters was scored over the first 6 days postpartum. Rat dams show consistent individual differences in the rate they lick and groom (LG) pups, allowing them to be categorized as high, low, or mid-LG mothers. The 100-day old male offspring of high and low-LG mothers were given the opportunity to learn food preferences for novel diets from conspecifics that had previously eaten these diets ("demonstrators"). Offspring of high-LG mothers socially learned food preferences, but offspring of low-LG mothers did not. We administered oxytocin to subjects to address the hypothesis that it would increase the propensity for social learning, but there were no detectable effects. Our data raise the possibility that social learning propensities may be both relatively stable throughout life and part of a suite of traits "adaptively programmed" by early developmental experiences.

Effects of conditioned food aversions on nutritional behavior in humans

Conditioned food aversion (CFA) and taste aversion (CTA) are widely occurring phenomena mediating rejection of solids or liquids, the ingestion of which has induced the onset of post-ingestional malaise. It is a powerful and durable imprint learning that may influence food choice and intake in all animals, including humans. For ethical reasons, CTA has been extensively investigated in a wide variety of laboratory animal's species but only incidentally in humans. Nevertheless, convincing evidence has been provided that CFA and CTA learning are possible in a wide range of human subjects. The results in humans may have some limitations in accuracy since data are sparse, sometimes indirect, and poorly controlled. There is only limited information on the extent of CFA in the elderly since most studies have employed questionnaire and/or interview methods on young people (i.e. college students). The present review evaluates the literature derived both from laboratory animals and humans. In the first instance, the salient features of food and taste aversion learning and the neural mechanisms involved in this learning behavior will be examined. Then, the problems encountered when trying to assess the role of learned food and taste aversions in the nutritional status of healthy as well as sick young or elderly people will be considered. In particular, the importance of CFA on the nutritional status of cancer patients and treatment of alcoholism will be examined. It is concluded that the data are compelling enough to warrant further research and, some indications and recommendations are suggested.