Department of Clinical Psychological Science, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands.
Int J Obes (Lond). 2012 May;36(5):627-37. doi: 10.1038/ijo.2011.213. Epub 2011 Nov 8.
The aim of this functional magnetic resonance imaging (fMRI) study was to investigate reward-related brain activity in satiated overweight and healthy-weight participants in response to high-calorie palatable food pictures, when viewing the pictures without prior instructions (called unbiased viewing) versus imagining the taste of the shown pictures (called taste imagination). We predicted that neural activation in brain reward regions would be greater in overweight participants than in healthy-weight ones and that this difference between groups would be strongest during unbiased viewing.
Neural activation was measured using fMRI in 14 overweight (mean body mass index (BMI): 29.8 kg m(-2)) and 15 healthy-weight (mean BMI: 21.1 kg m(-2)) participants who were satiated, in response to palatable and unpalatable high-calorie and low-calorie food pictures, presented in an event-related design during two conditions: unbiased viewing (no prior instructions) versus taste imagination.
A group × condition interaction was found in 14 brain regions involved in food reward processing during the presentation of high-calorie palatable food stimuli. During the taste imagination condition, neural activation in these regions was greater in the overweight participants than in the healthy-weight ones. Contrary to our expectations, the opposite pattern was observed during unbiased viewing: activation in reward regions in the overweight participants was reduced compared with the healthy-weight ones. In all brain reward regions except for the left amygdala, the group × condition interaction was specific to high-calorie palatable food stimuli.
Greater reward activity in the overweight participants compared with the control group when imagining taste may represent an increased reward response induced by high-calorie palatable food. During unbiased viewing, reduced reward activation in the overweight participants compared with those with a healthy weight may reflect avoidance of high-calorie palatable food stimuli. Taken together, this pattern of activation may reflect ambivalence in the overweight group between desire for (in the taste imagination condition) and avoidance of (in the unbiased viewing condition) high-calorie palatable food stimuli.
本功能磁共振成像（fMRI）研究旨在探讨在饱食状态下超重和健康体重的参与者在观看高热量美味食物图片时，在没有预先指令的情况下（称为无偏观看）与想象所展示图片的味道（称为味觉想象）时，与奖赏相关的大脑活动。我们预测，超重参与者的大脑奖赏区域的神经激活会高于健康体重者，并且组间差异在无偏观看时最强。
我们使用 fMRI 测量了 14 名超重（平均体重指数（BMI）：29.8kg/m²）和 15 名健康体重（平均 BMI：21.1kg/m²）参与者在饱食状态下对美味和不美味的高热量和低热量食物图片的神经激活，这些图片在事件相关设计中呈现，在两种条件下：无偏观看（无预先指令）与味觉想象。
在呈现高热量美味食物刺激时，14 个涉及食物奖赏处理的大脑区域中发现了组×条件的相互作用。在味觉想象条件下，超重参与者的这些区域的神经激活高于健康体重者。与我们的预期相反，在无偏观看时观察到相反的模式：与健康体重者相比，超重参与者的奖赏区域的激活减少。除了左侧杏仁核外，所有大脑奖赏区域的组×条件相互作用均特定于高热量美味食物刺激。
与对照组相比，超重参与者在想象味道时的奖赏活动增加可能代表高热量美味食物引起的奖赏反应增加。在无偏观看时，与健康体重者相比，超重参与者的奖赏激活减少可能反映了对高热量美味食物刺激的回避。总的来说，这种激活模式可能反映了超重组对（在味觉想象条件下）和回避（在无偏观看条件下）高热量美味食物刺激的矛盾心理。
