Generalization of Object Localization From Whiskers to Other Body Parts in Freely Moving Rats.

Rats can be trained to associate relative spatial locations of objects with the spatial location of rewards. Here we ask whether rats can localize static silent objects with other body parts in the dark, and if so with what resolution. We addressed these questions in trained rats, whose interactions with the objects were tracked at high-resolution before and after whisker trimming. We found that rats can use other body parts, such as trunk and ears, to localize objects. Localization resolution with non-whisking body parts (henceforth, 'body') was poorer than that obtained with whiskers, even when left with a single whisker at each side. Part of the superiority of whiskers was obtained via the use of multiple contacts. Transfer from whisker to body localization occurred within one session, provided that body contacts with the objects occurred before whisker trimming, or in the next session otherwise. This transfer occurred whether temporal cues were used for discrimination or when discrimination was based on spatial cues alone. Rats' decision in each trial was based on the sensory cues acquired in that trial and on decisions and reward locations in previous trials. When sensory cues were acquired by body contacts, rat decisions relied more on the reward location in previous trials. Overall, the results suggest that rats can generalize the idea of relative object location across different body parts, while preferring to rely on whiskers-based localization, which occurs earlier and conveys higher resolution.

Making a global sensation: Vanilla flavor, synthetic chemistry, and the meanings of purity.

How did vanilla, once a rare luxury, become a global sensation? Rather than taking the vanilla flavor of vanilla beans as a pre-existing natural fact, this essay argues that the sensory experience that came to be recognized as vanilla was a hybrid artifact produced by an expanding global trade in a diverse set of pleasurable substances, including cured beans from artificially pollinated vanilla orchids, synthetic vanillin, sugar, and a far-flung miscellany of other botanical and chemical materials. Global trade and large-scale production resulted not in the production of a homogenous, stable commodity, but in a range of local vanillas, heterogeneous mixtures with a range of qualities and virtues. As local commercial and regulatory interests competed to define the origins, and thus the market value, of authentic vanilla flavor, scientific experts were called upon to adjudicate these rival claims. In the United States, these debates played out in the context of the 1906 Pure Food and Drug Act, where efforts to define and chemically enforce a 'standard' vanilla extract, in contradistinction from adulterated, 'imitation' extracts, clashed with the interests of makers and users of both synthetic and 'genuine' vanilla flavorings. As regulatory chemists grappled with the growing variety of vanillas, they were required to determine the appropriate chemical components of genuine vanilla, and consequently to delimit the subjective sensory effects proper to the flavor. Nonetheless, the materials, experiences, and meanings popularly associated with vanilla flavor continued to exceed the limits prescribed by officials.