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.