高功能ASD儿童利他行为特征及其相关脑机制

Altruism, defined as any behavior that increases others' fitness at a cost of the performers' benefit, is a senior strategy in social interaction. However, whether the dysfunction of “social brain” in Autism Spectrum Disorder (ASD) affect their altruistic behavior remains unknown. Furthermore, it is not known whether ASD possess altruistic consciousness. Therefore, according to previous researches, we hypothesize that the difficulties of social interaction in ASD may root in their abnormal altruistic consciousness and behavior, and some related neural mechanisms may be involved in the process. To test this hypothesis, we design two experimental paradigms—the Dictator Game (DG) and the Ultimatum Game (UG) —based on the game theory of classical neuroeconomics to assess altruistic behavior among children with high functional autism (HFA) and those typical developmental children . Event-related functional magnetic resonance imaging (fMRI) and event-related potential (ERP) are applied to record the brain function when children are making decisions. We aim to find (1) whether children with ASD have the intention of altruism? (2) If ASD do have altruistic consciousness, whether the unique activity in some brain regions, such as the amygdale, the striatum, the orbito frontal cortex and the anterior cingulate cortex, can predict their behavior? (3) Whether DG and UG could reflect the processing mechanisms underlying altruism in ASD effectively? (4) Whether this mechanism could reflect the characteristics of altruistic decision making in ASD? Better understanding these has important implications and will provide important inspirations and clues for the treatment of ASD.

利他（altruism）是人的社交本能行为。孤独症谱系障碍（ASD）“社会脑”功能损害是否罹及其利他行为，ASD是否存在利他意识迄今仍不明确。据前研究，假设ASD 社交孤立可能源于利他意识及利他行为异常，并存在相应的神经机制。拟根据经典神经经济学（neuroeconomics）游戏理论，设计决策者游戏（DG）和最后通牒游戏（UG）实验范式，靶刺激诱导记录高功能ASD及正常儿童的事件相关脑功能磁共振（fMRI）和事件相关电位（ERP）特征，以分析探明（1）ASD 是否具备特异的利他意识，它能否驱动其利他行为表现？（2）若ASD存在利他意识，其杏仁核、纹状体、眶额叶和前扣带回等脑区激活状态可否预测其行为反应？（3）DG和UG实验能否有效反映ASD的利他意识加工机制？（4）这种机制能否反映ASD存在利他决策的加工异常？探明这点对ASD矫治极有参考意义。

利他（altruism）是人的社交本能行为。孤独症谱系障碍（ASD）“社会脑”功能损害是否罹及其利他行为，ASD是否存在利他意识迄今仍不明确。据前研究，假设ASD 社交孤立可能源于利他意识及利他行为异常，并存在相应的神经机制。本研究根据经典神经经济学游戏理论，设计决策者游戏（DG）和最后通牒游戏（UG）实验范式，靶刺激诱导记录高功能ASD及正常儿童的事件相关脑功能磁共振（fMRI）和事件相关电位（ERP）特征。获得的主要研究成果如下：1）正常学龄期儿童中77.8%进行了利他性惩罚，其行为表现和反应速度均与分享值即行为成本密切相关；利他分享随年龄增长而增加；智力、ToM和抑制控制能力对儿童利他分享行为的作用仅发现延迟满足能力对儿童是否分享有影响；而儿童的利他惩罚行为与智力水平有关，智商高者愿意付出更大的代价惩罚不公平行为。2）高功能ASD 儿童的利他分享行为低于同龄正常儿童。但决定分享后，ASD 儿童的平均分享程度与正常儿童相近。提示ASD 儿童仅存在对“是否分享”的决策异常，其原因可能是利他动机缺陷。23.08%的高功能ASD 儿童选择了利他惩罚，并且其利他惩罚决策模式与正常儿童一致：接受率均随分享值增长而升高；ASD儿童的利他行为异常并不能用社会认知缺陷解释，利他分享（是否分享）和 ToM 均与疾病有关。提示是否具有利他分享（利他动机）可能成为鉴别 ASD 的一个重要参校。 UG任务下，ASD 儿童的 FRN 振幅高于同龄正常儿童，表明其存在奖赏加工功能异常。ASD 儿童的 FRN 潜伏期显著长于正常儿童，其对刺激信息的神经加工反应更慢或效率更低；具有利他行为的ASD儿童的同伴行为和亲社会行为表现亦优于无利他行为的ASD儿童。3）高孤独特质（HAT）儿童的利他分享程度与高功能ASD儿童相近。但HAT 儿童利他分享程度与认知灵活性和心理理论能力呈正向关系，ASD 儿童则无此关联性，高功能ASD 和HAT儿童在第三方决策任务下的神经电生理反应相近，HAT 儿童神经电生理反应与认知灵活性相关，而 ASD 儿童则无此关联性，提示 ASD和HAT 儿童利他决策相关神经心理机制存在差异。