Brain Response to Aversive Taste for Investigating Taste Preference

To clarify the intrinsic food preference mechanism, we investigated brain neurophysiological responses to unpleasant gustatory stimuli using electroencephalogram (EEG) and near-infrared hemoencepalogram (NIR-HEG) simultaneously. A conventional delayed response task based on Go/Nogo paradigm was adopted to extract real brain response components from spontaneous background signals. We found excessive evoked EEG potential responses to both bitter and sour stimuli, while we didn’t find excessive changes in purified water condition. These potentials appeared before P3, hence, they potentially predicted unconscious attention to the gustatory stimuli. We also identified a late contingent negative variation (CNV) and corresponding P3 for sour stimulus. In addition, NIR-HEG responses showed relative changes for every stimulus and we considered that these NIR-HEG signal changes were attributed to the prefrontal cortex activity for regulating negative emotional valence against aversive tastes typically including sour and bitter. In spite of limitation to timing accuracy of taste presentations, the early markers found in this study could be fundamentals for investigating individual food preference.

Relationship between Taste Sensitivity and Eating Style in Japanese Female University Students

This study investigated the relationship between taste sensitivity, the frequency and the preference for eating foods rich in zinc, dietary habits, and restrained eating among Japanese female undergraduate students. Forty-three subjects be-tween the ages of 20 and 22 participated in this study. After a taste-sensitivity test for sweetness and saltiness the stu-dents completed a food list indicating the intake frequency and preference of foods rich in zinc and their eating habits. The students were divided into four groups: high salt-taste sensitivity (SA-HG), low salt-taste sensitivity (SA-LG), high sweet-taste sensitivity (SW-HG), and low sweet-taste sensitivity (SW-LG). Individuals in the SA-HG group ate more foods rich in zinc and were more concerned with their health than those in the SA-LG group. Further, the SW-LG group ate more convenience foods than the SW-HG group. High salt-taste sensitivity could be predicted by eating more but less preference of foods rich in zinc, less snacking, and greater regularity of meals. On the other hand there is a signifi-cant positive relationship between the frequencies of eating and preference for foods rich in zinc. This means the results were inconsistent, further research is needed to clarify this point.

An fNIRS Research on Prefrontal Cortex Activity Response to Pleasant Taste

Functional Near-Infrared Spectroscopy (fNIRS), as a non-invasive neuroimaging technique, was used to monitor the activation of prefrontal lobe on human brain during sweet taste processing. The primary aim of the present study was to find the region of interest (ROI) which is related to sweetness, and make further understanding of the central organization of taste. Based on event-related design, the experiments were performed with 16 volunteers by sweet taste stimulus. It was confirmed that the prefrontal cortex (PFC) is involved in sweet taste processing and fNIRS provided an alternative way for studying taste-related brain function under more natural conditions. This study might be effective for detecting the accession area in the cortex of sweet taste and helpful for studying on human feeding and taste disease like taste dyspepsia or disorder.

Activation of Human Prefrontal Cortex to Pleasant and Aversive Taste Using Functional Near-Infrared Spectroscopy

The aim of the study was to investigate the representation of taste in human prefrontal cortex (PFC), in particular, to compare the representation of a pleasant and an aversive taste using functional near-infrared spectroscopy (fNIRS), so as to obtain further understanding of the taste preference mechanism. The pleasant stimulus used was sweet taste (10% sucrose), and the unpleasant stimulus was sour taste (1% critic acid). Based on event-related design, the experiments were performed with 16 healthy volunteers using the OEG-16 fNIRS sensor. A general linear model was used to analyze the collected data. For the concentration change of oxygenated hemoglobin (ΔoxyHb), we found that significant deactivation was induced by sweetness and sourness in parts of the frontopolar area, orbitofrontal area and dorsolateral prefrontal cortex in bilateral hemisphere of human brain. And the right PFC showed different levels of activation between sweetness and sourness. In addition, brain activities were more sensitive to sourness than sweetness. Finally, we confirmed that the PFC was involved in sweet and sour taste processing, and fNIRS provided an alternative way for studying taste-related brain function under more natural conditions.