Basic Taste Stimuli Elicit Unique Responses in Facial Skin Blood Flow

Hideaki Kashima,Naoyuki Hayashi,Attila Szolnoki

doi:10.1371/journal.pone.0028236

Abstract

Facial expression changes characteristically with the emotions induced by basic tastes in humans. We tested the hypothesis that the five basic tastes also elicit unique responses in facial skin blood flow. Facial skin blood flow was measured using laser speckle flowgraphy in 16 healthy subjects before and during the application of basic taste stimuli in the oral cavity for 20 s. The skin blood flow in the eyelid increased in response to sweet and umami taste stimuli, while that in the nose decreased in response to a bitter stimulus. There was a significant correlation between the subjective hedonic scores accompanying these taste stimuli and the above changes in skin blood flow. These results demonstrate that sweet, umami, and bitter tastes induce unique changes in facial skin blood flow that reflect subjective hedonic scores.

Highlights

The gustatory characteristics of foods exert effects on eating behaviors and judgments of their acceptability so as to avoid the ingestion of toxic and unpleasant foods [1]
Some previous studies have suggested that the basic tastes induce specific heart rate and finger skin resistance responses according to the associated hedonic valence or emotion [4,5,6]
Sweet and umami stimuli were reflected in the eyelid skin blood flow, such that the blood flow increased with the hedonic score (Fig. 2a, b)

Summary

Introduction

The gustatory characteristics of foods exert effects on eating behaviors and judgments of their acceptability so as to avoid the ingestion of toxic and unpleasant foods [1]. One way of conferring these characteristics to one’s peers is by facial expressions, since those associated with the intake of foods with pleasant and unpleasant tastes are consistent among different cultures, races, and individuals [2] This has led to facial expression being used to evaluate objective gustatory senses [3]. Some previous studies have suggested that the basic tastes induce specific heart rate and finger skin resistance responses according to the associated hedonic valence or emotion [4,5,6]. Our previous study suggested that gustatory information increases the blood flow in the gastrointestinal tract [7] Such responses cannot be used as a tool by which to communicate with peers since most of them occur inside the body (i.e., playing a functional role in digestion). It is unknown whether ANS responses such as changes in facial skin blood flow mirror gustatory information

Methods

Results

Conclusion