Taste sensing and sugar detection mechanisms in Drosophila larval primary taste center

Despite the small number of gustatory sense neurons, Drosophila larvae are able to sense a wide range of chemicals. Although evidence for taste multimodality has been provided in single neurons, an overview of gustatory responses at the periphery is missing and hereby we explore whole-organ calcium imaging of the external taste center. We find that neurons can be activated by different combinations of taste modalities including of opposite hedonic valence and identify distinct temporal dynamics of response. Although sweet sensing has not been fully characterized so far in the external larval gustatory organ, we recorded responses elicited by sugar. Previous findings established that larval sugar sensing relies on the Gr43a pharyngeal receptor, but the question remains if external neurons contribute to this taste. Here we postulate that external and internal gustation use distinct and complementary mechanisms in sugar sensing and we identify external sucrose sensing neurons.

Augmented reality flavor: cross-modal mapping across gustation, olfaction, and vision

Gustatory display research is still in its infancy despite being one of the essential everyday senses that human practice while eating and drinking. Indeed, the most important and frequent tasks that our brain deals with every day are foraging and feeding. The recent studies by psychologists and cognitive neuroscientist revealed how complex multisensory rely on the integration of cues from all the human senses in any flavor experiences. The perception of flavor is multisensory and involves combinations of gustatory and olfactory stimuli. The cross-modal mapping between these modalities needs to be more explored in the virtual environment and simulation, especially in liquid food. In this paper, we present a customized wearable Augmented Reality (AR) system and olfaction display to study the effect of vision and olfaction on the gustatory sense. A user experiment and extensive analysis conducted to study the influence of each stimulus on the overall flavor, including other factors like age, previous experience in Virtual Reality (VR)/AR, and beverage consumption. The result showed that smell contributes strongly to the flavor with less contribution to the vision. However, the combination of these stimuli can deliver richer experience and a higher belief rate. Beverage consumption had a significant effect on the flavor belief rate. Experience is correlated with stimulus and age is correlated with belief rate, and both indirectly affected the belief rate.

Preference and effect of gustatory sense on sugar-feeding of fire ants

Background The red imported fire ant is one of the notorious species of ants all over the world. Sugar is one of the most important components of food and necessary for the survival of ants. Because more than 70% food of fire ants is honeydew produced by Homopteran insects such as aphids and scales. Methodology It is well known that beetles, flies, and honey bees can recognize the sugar taste through their legs and antennae, but in the case of fire ants, no records regarding gustatory sense were published. In the current study, considering the importance of sugar bait, we investigated the gustatory sense of the fire ant workers to sucrose via behavioral sequence and gustatory behavior. First, the feeding sequence (ethogram) of the fire ant workers on most preferred sugar (sucrose) solution was observed and categorized. Secondly, the gustatory behavior of treated fire ant workers (without flagellum and foreleg tarsi treated with HCL solution) was observed on the sucrose solution. In addition, using scanning electron microscopy (SEM) techniques, we identified the possible porous sensilla types on antenna flagellum and foreleg tarsi of fire ant workers. Results Based on the results of feeding sequence, foreleg tarsi of workers were the main body appendages in the detection of the sucrose droplet as compared to antennae flagellum and palps. Feeding time of treated workers with HCL solution was significantly decreased on sucrose solution as compared to those workers having no flagellum. While both types of treated workers have less feeding time in comparison to normal workers. Based on the results of feeding sequence analysis and feeding time, it is indicating that the foreleg tarsi of workers play a more important role in the detection of sucrose solution as compared to antennae flagellum. Based on the SEM results, sensilla chaetic, trichoid II, and basiconic I and II have a clear pore at their tip. This study provides a substantial basis for elucidating the gustatory function of antennal and tarsal sensilla on appendages of fire ant workers to sugars and further baits improvement for the management of fire ants.

Comparison with Amount of Gustatory Sense and Nasal Skin Temperature

We compared study the amount of gustatory sense and changes in nasal skin temperature. Gustatory stimulation used saltiness and acidity that was four basic tastes. The amount of stimulation was changed and presented it. To determine the amount of gustatory sense, we used in nasal skin temperature as an objective index and the visual analog scale (VAS) as a subjective index. These indexes were compared and evaluated. That maximum temperature displacement, temperature drop, and VAS displacement increase with the amount of stimulation.

Importance of lipolysis in oral cavity for orosensory detection of fat

Lingual lipase is usually secreted from von Ebner's glands, although there is great variation between species. Lingual lipase is thought to be an auxiliary enzyme for fat digestion and absorption in mammals; however, the reason for lipolysis in the oral cavity is not known. We focused on the gustatory sense and investigated the significance of lingual lipase in the perception of a fat taste by using orlistat, a potent lipase inhibitor. Five-minute two-bottle preference tests demonstrated that the addition of orlistat diminished the preference for triacylglycerides but not for free fatty acids. Radioactive triolein applied on rats' circumvallate papilla revealed that lingual lipase was released continuously to generate significant amounts of fatty acids and other lipolytic products within 1–5 s, which was enough time to taste fat. These findings suggest that lingual lipase is released to perceive the taste of triacylglycerides and to find nutritive lipids in food.