Figure 1.
(A) Each trial started with the presentation of a fixation cross followed by an image of either a high-calorie or a low-calorie food or a non-food item. Following a variable inter-stimulus interval, a neutral taste stimulus was presented. After the offset of the taste, participants had to first rate the taste intensity and pleasantness and then categorize the image preceding the taste into food vs. non-food items. They were naïve as to the task-irrelevant, i.e. high- and low-calorie image categories. (B) To illustrate the variety of high-calorie stimuli (160–717 kcal/100 g) and low-calorie stimuli (12–151 kcal/100 g), four pictures of each category are presented. High-calorie: Lamb-chops, Salmon, Pizza, Pastry. Low-calorie: Beans, Water melon, Yoghurt, Pasta w. Tomato Sauce.
Figure 2.
(A) Exemplary group-averaged ERP waveforms from electrode Fz, Cz, and Pz. Taste onset is at time 0 ms. (B) Time course of group-averaged ERP waveforms from 64 electrodes to the taste stimuli (taste onset = at 0 ms) averaged across all conditions. (C) The temporal extent of the topographic map series is indicated as colored segments under the global field power curve. (D) Topographic maps (scaled to the maximum; top view) correspond to the temporal succession of segments in (C). Hot and cold colors reflect positive and negative ERP amplitudes, respectively.
Figure 3.
Statistical contrasts of LAURA source estimations computed for taste stimuli when preceded by high-calorie versus low-calorie images. Time periods were obtained from the topographical cluster analysis. Color scales represent t-values with positive values indicating stronger activity during taste perception preceded by high-calorie than low-calorie images and negative values indicating increased activity when taste was preceded by low- as compared with high-calorie images. MFG = middle frontal gyrus, INS = insula, ACC = anterior cingulate cortex, OFC = orbitofrontal cortex, PHI = parahippocampal gyrus, PCG = postcentral gyrus, IOG = inferior occipital gyrus.
Figure 4.
Correlations between changes in source strength and taste pleasantness ratings.
Correlations were determined between changes in brain activation (i.e. high-calorie minus low-calorie) in the OFC and right anterior insula and changes in participant's taste ratings (i.e. high-calorie minus low-calorie). The source strength was determined at the voxel exhibiting the maximum activity within the region of interest for each participant during the 176–236 ms period for the OFC and during the 357–500 ms period for the right insula.