A Functional MRI Study Of Sweet Taste And Sour Taste Cortical Areas In Humans

Objective: To investigate and measure brain activation in response to sweet taste and sour taste stimulus by using fMRI-BOLD on the advanced MRI system, to explore the activation mode and characteristic, then analyse the similarity and difference between localizations of sweet and sour taste cortical areas in human brain and make further understanding about the central organization of taste.Materials and Methods: fMRI-BOLD scan covering the whole brain was performed on two groups of 29 right-handed healthy human subjects during event-relate designed stimulation with sweet taste or sour taste compared with tasteless control.(14 for sweet and 15 for sour).The fMRI data was analyzed by SPM2 and SPSS13.0 software with statistic t-test to generate the activation map and correlated data.Results: 1.Using sweet stimulus, the strongest activated cortical areas were orbitofrontal cortex(the left are superior), insula and operculum, then were inferior parietal lobule, superior frontal gyms , cingulate gyrus, superior parietal lobule and thalamus. The activated area also included superior temporal gyri, middle temporal gyri and middle frontal gyrus.2. Using sour stimulus, the strongest activated cortical area were orbitofrontal cortex(the left are superior), superior frontal gyrus, insula and operculum, inferior parietal lobule, then were superior frontal, cingulate gyrus and thalamus. The other activated areas included middle temporal gyri and inferior frontal gyrus, middle frontal gyrus, gyrus rectus, parahippocampal gyrus.Conclusions: 1. The majority activated areas are similar, including insula and operculum and orbitofrontal cortex which are described as primary and secondary gustatory cortex by mostly scientist. The other common areas include superior frontal gyrus , inferior parietal lobule, cingulate gyrus, superior parietal lobule and thalamus.2. Compared sour taste with sweet taste, the range of activated areas of the sour taste is lager than the one's of sweet. Whereas speaking of the intensity of the majority common areas or the total activated areas, the latter is stronger than the former.3. Incomplete gustatory lateralization has been occurred in all of the human subjects. the primary gustary cortex have no lateralization, while the secondary gustary cortex shows left lateralization, especially in the orbitofrontal cortex.4. The fMRI data shows the complexity of the activation of human brain by using sweet or sour taste stimulate.