食物线索对肥胖儿童抑制控制的影响及其神经心理机制研究

Inhibitory control was significantly associated with body weight, but our previous studies failed to find differences between obese and normal-weight children in classic inhibitory control experiments. According to the incentive sensitization theory, food cues were regarded as high reward-sensitive stimuli, can strongly activate reward-related brain areas, which should induce worse performance on inhibitory control tasks. However, whether exposure to food cues specifically decrease inhibitory control in obese children, namely the role of food cues on inhibitory control and its neuropsychological mechanism are unknown. We hypothesized that obese children have insufficient inhibitory control over specific stimuli, which makes it difficult to suppress selective visual preference and information processing preference for food cues. Therefore, based on our previous studies, we designed stop-signal task and Go/No-Go task, including three stimuli materials: low (neutral stimuli), medium (low calorie food stimuli) and high (high calorie food stimuli). The inhibitory control of both obese children and their matched normal weight partners will be assessed with these two paradigms, while the infrared eye tracking and event-related potentials techniques will be used during these tests. The purpose of present study is to explore (1) The inhibitory control performance of obese children on different stimulus, and whether food cues could drive selective visual preference in obese children? (2) The effect of food cues on inhibitory control and its neural electrophysiological response. Better understanding of aforementioned issues could provide new insights into the intervention for childhood obesity.

抑制控制参与体重调控，但我们前期研究发现肥胖与正常体重儿童在经典抑制控制实验中表现并无差异。根据刺激−敏感化理论，食物线索作为高奖励敏感性刺激，强烈激活大脑奖赏区，理应诱发抑制控制任务更差表现。然而，肥胖儿童在食物线索环境中是否存在特异的抑制控制降低，即食物线索对抑制控制影响如何，其神经心理机制又如何表征，尚不清楚。我们假设：肥胖儿童对特定刺激抑制控制不足，难以抑制对食物线索的选择性视觉偏好及信息加工偏好。因此，基于原有实验，设计低（中性物品）、中（低热量食物）和高（高热量食物）三种刺激的停止信号任务和Go/No-Go任务实验，采用红外眼动和事件相关电位技术对一组肥胖和体重正常儿童进行测试，探索（1）肥胖儿童对不同奖励敏感性刺激的抑制控制特征，是否对食物线索表现出选择性视觉偏好;（2）可否通过神经电生理技术探明食物线索影响肥胖儿童抑制控制的神经心理机制。探明上述，可为肥胖干预提供重要启示。

肥胖儿童的抑制控制是否存在缺陷是近年研究关注和探索的热点。抑制控制参与进食行为的调控，抑制控制不足则难以抑制进食冲动，从而增加进食行为导致肥胖。但我们前期研究发现肥胖与正常体重儿童在经典抑制控制实验中表现并无差异。根据刺激−敏感化理论，刺激的奖励敏感性不同导致大脑奖赏脑区激活程度存在差异。食物线索作为高奖励敏感性刺激，高度激活大脑奖赏脑区，需更强的抑制控制卷入来抑制进食冲动，理论上会导致个体在抑制控制任务中表现更差。因此，本研究设计了低（中性物品）、中（低热量食物）和高（高热量食物）三种刺激的停止信号任务和Go/No-Go任务实验，采用红外眼动和ERP对肥胖和体重正常儿童进行测试。研究发现调整混杂因素后，超重肥胖组执行功能各因子得分均高于正常体重组（P＜0.001），提示超重肥胖儿童执行功能降低。在停止信号任务中，超重肥胖组儿童对高热量图片刺激的成功抑制率均较正常体重组儿童低，且停止信号反应时SSRT均较长，差异具有统计学意义（p<0.05）。在Go/No-Go 任务中超重肥胖组儿童在NoGo 高热量任务中错误率方面较正常体重儿童高，差异具有统计学意义，（p<0.001）。提示超重肥胖儿童对于高热量图片的抑制控制能力更差。在眼动实验停止信号任务中肥胖组儿童对不同热量刺激图片的首次注视时间和注视时间均更长（P<0.01），在注视时长所占比例中对高热量食物图片的注视时间最长（P<0.01）；在Go/No-Go 任务中，超重肥胖儿童对高热量食物图片的注视时长较正常体重儿童更长（P=0.02），而在注视点方面，超重肥胖儿童较正常体重儿童更少（P=0.05）。提示肥胖儿童对于高热量食物图片食物线索表现出选择性视觉偏好。在ERP实验中，我们也发现儿童对于高热量食物，低热量食物以及中性食物的刺激，所产生的脑电信号存在差异，超重肥胖组儿童的N200波较正常对照组儿童潜伏期更长，波幅更大，提示前额叶抑制控制功能受损。综上，食物线索对儿童抑制控制能力产生影响，超重肥胖儿童对于高热量食物线索的抑制控制更差，为肥胖预防和干预提供新思路。