对食物选择的冲动性决策的静息态fMRI研究

发布时间：2018-06-06 18:11

本文选题：冲动性 + 强化学习　；参考：《西南大学》2017年硕士论文

【摘要】：不管是成人还是儿童如今超重和肥胖的趋势都急剧增加。世界健康组织WHO指出肥胖和超重在当今是最严重的公共健康问题之一。日益增长的超重群体受到更多慢性疾病的威胁。虽然肥胖有很大一部分受基因的影响,过去二十多年来的研究发现日益增长的肥胖与环境的作用不可小觑。最近几十年间的快速增长和我们社会发展形成一个现在的致胖环境的因素极为相关。比如人们的活动受到限制,高脂高糖和高能食物的易获得性。当然,除此以外还有一些心理因素也会导致过度进食。个体在奖赏敏感性和冲动性上的差异或许可以预测对食物的偏好和进食,并且,饮食模式深深地扎根于当今社会,比如高能高脂的食物已经证明会对大脑强化敏感性和冲动控制系统有重要影响。其中一个重要因素就是对食物的冲动性选择。食物选择的冲动性是指选择进食主要根据即时的奖赏性即当下进食在味觉上的享受而缺乏对长期进食该食物对健康的影响。进食行为的冲动性也是指进食动力主要是即时的奖赏性而不是长期进食带来的负性结果。越来越多的动物模型以及人类脑成像的证据表明物质相关的决策冲动或者肥胖与背侧纹状体的功能降低有关。这种现象或许为学习线索的敏感性降低以及背侧纹状体的奖赏功能降低提供了支持的证据。然而,对于食物相关的冲动性决策在静息态下背侧纹状体的内部功能如何还不得而知。为了了解这个问题,我们采用三个研究以及静息态功能磁共振技术(rs-fMRI)来测试成年女性的大脑活动如何。实验选取了79名女性被试,年龄在17-27周岁,平均年龄为20.59。BMI在15.56-28.94之间。实验材料是170张不同的食物图片包括85张高能量食物图片和85张低能量食物图片。采用静息态磁共振来考察成年女性的大脑活动,我们还让被试进行食物评定任务,在食物评定任务中被试要求根据他们对呈现食物的主观味觉也就是主观上感觉非常喜欢到非常不喜欢进行评定;他们如果长期进食这种食物对健康的影响也进行客观的评定,程度为非常不健康到非常健康,最后从十张图片(五张高能量和五张低能量食物图片)中选取他们各自在味觉和健康上评定为中性的图片作为参考图片,然后在决策任务中让他们一一将呈现的图片与参考的食物图片进行比较选择吃参考的食物还是呈现的食物。研究一的结果显示,只有对高能量食物的决策强度与食物的冲动性决策相关,冲动性决策与低能量食物的决策强度并无关系。因为高能量食物的决策强度与冲动性量表BIS-11呈正相关,与DEBQ-EX分量表也呈显著相关。静息态磁共振的结果显示食物相关的冲动性决策越高背侧纹状体尤其是背侧尾状核的自发性局部一致性越低,而食物相关的冲动性决策越高双侧楔叶的自发性局部一致性ReHo值更高。这一结果可能预示着尾状核的反应是与冲动性相关。背侧纹状体(尾状核)在高冲动性个体中对奖赏反馈物的感觉钝化使得他们更容易忽略奖赏可能会带来的不利结果。鉴于楔叶在视觉注意以及对视觉加工的基本阶段的重要作用,我们的结果进一步证实了对食物决策有冲动性的个体在注意力上更容易或保持对美味高能食物的关注,并且表现出对食物奖赏的预期。在随后研究二的功能连接中我们以双侧楔叶和尾状核为种子点发现食物相关的冲动性决策越高尾状核与壳核的功能连接强度越低。这一结果揭示了食物选择相关的高冲动性决策个体从目标指导行为向习惯化行为的转换。背侧尾状核到左侧眶额叶皮层的功能连接强度与对高能量食物图片的决策强度呈正相关。这或许是背侧尾状核和外侧眶额叶皮质内部整合功能的增加,而这种功能的提高有助于编码美味食物的奖赏价值,表现出高度自动化的特质。左侧楔叶到右侧海马旁回与高能量食物的决策呈显著正相关。对食物选择的冲动性越高右侧楔叶到右侧辅助运动区的功能连接强度越强。这说明食物选择高冲动性的个体在视觉网络与感觉运动网络具有高敏感性。研究三进一步发现六个月后BMI变化率越高和背侧纹状体(尾状核)和壳核的功能连接强度越低。这个结果可能揭示了在决策中背侧尾状核对奖赏信号的敏感性降低伴随着目标指导行为(主要由背侧尾状核调节)向习惯化行为(主要由壳核调节)的转变,而这种转变与未来体重的增加以及冲动性的增强有关。总之,此研究拓宽了我们对食物相关的冲动性决策在静息态下的神经基础的认识,也为未来体重增加提供了生物标记的证据。
[Abstract]:The World Health Organization WHO points out that obesity and overweight are one of the most serious public health problems today. The growing overweight group is threatened by more chronic diseases. Although obesity has a large part of the gene, it has been in the past more than 20 years. The study found that growing obesity and the role of the environment can't be underestimated. The rapid growth in the last few decades has been extremely related to the formation of a present fatter environment in our society, such as people's activities being restricted, high fat and high sugar and high energy food availability. Excessive eating. Individual differences in reward sensitivity and impulsiveness may predict food preferences and eating, and dietary patterns are deeply rooted in today's society, such as high energy and high fat food, which has proved to have an important impact on the brain's enhanced sensitivity and impulse control system. One of the important factors is that Impulsiveness of food. The impulsiveness of food selection refers to the choice of eating mainly based on immediate reward, that is, the enjoyment of food on the taste, and the lack of effect on the health of the food. The impulsivity of eating behavior is also the motive of feeding motivation mainly in the immediate reward rather than the negative result of long-term eating. More and more animal models and evidence for human brain imaging have shown that material related decision impulses or obesity are associated with decreased function in the dorsal striatum. This phenomenon may provide evidence for lower sensitivity of learning clues and lower reward function in the dorsal striatum, however, for food related impulsivity. In order to understand this problem, we used three studies and resting state functional magnetic resonance (rs-fMRI) to test the brain activity of adult women. The experiment selected 79 female subjects at age 17-27, and the average age was 20.59.BMI in 15.56-28. .94 between 170 different food pictures, including 85 high energy food pictures and 85 low energy food pictures. Resting state magnetic resonance (MRI) was used to examine the brain activity of adult women. We also asked the subjects to carry out the food assessment task. In the food assessment task, the subjects were asked to be based on their subjective taste for food. Subjectively, it feels very dislike to be very dislike of evaluation; if they eat the food for a long time, they also have an objective assessment of the health effects. They are very unhealthy and very healthy. Finally, they choose their taste and health from ten pictures (five high energy and five low energy food). The results show that only the decision intensity for high energy food is associated with impulsive decision making for food, impulsive decision making and low energy. The decision intensity of the amount of food was not related, because the decision intensity of high energy food was positively correlated with the Impulsivity Scale BIS-11, and was also significantly related to the DEBQ-EX subscale. The higher the spontaneous local consistency ReHo of the bilateral cuneate is higher, the higher the relative impulse decision is, the result may indicate that the reaction of the caudate nucleus is associated with impulsivity. The dorsal striatum (caudate nucleus) in the highly impulsive individual's sensory passivation of reward feedback makes them easier to ignore the adverse results that the reward may bring. In view of the importance of the wedge in visual attention and the basic stage of visual processing, our results further confirm that individuals who are impulsive to food decision-making are more likely to focus on the attention of the delicacy high energy food, and show the expectation of food rewards. Bilateral cuneate and caudate nuclei found that the higher the food related impulse decision was, the higher the functional connection strength of the caudate nucleus and the putamen was lower. The results revealed the transition from the target directed behavior to the habitual behavior of the food selection related high impulsive decision making individuals. The functional connectivity intensity of the dorsal caudate nucleus to the left orbital frontal cortex. There is a positive correlation with the decision intensity of high energy food pictures. This may be an increase in the internal integration of the dorsal caudate nucleus and the lateral orbital frontal cortex, which helps to encode the rewarding value of the delicious food, and shows a highly automated trait. The left cuneate leaves to the right side of the hippocampus and the high energy food The higher the impulsiveness for food selection, the stronger the functional connectivity of the right cuneate to the right auxiliary motor area. This shows that the individuals with high impulsivity in the food selection have Gao Min sensibility in the visual network and sensory network. Study three further found that the higher the rate of BMI changes after six months and the dorsal striatum (caudate nucleus) and the shell The lower the strength of the functional connection of the nucleus. This result may reveal that the sensitivity of the dorsal caudate nucleus to the reward signal in the decision is accompanied by the direction of the target (mainly regulated by the dorsal caudate nucleus) to the habitual behavior (mainly regulated by the putamen), which is associated with an increase in the future weight and the enhancement of impulsiveness. In conclusion, this study broadens our understanding of the neural basis of food related impulsive decision making in the resting state, and also provides evidence of biomarkers for future weight gain.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：B842

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