Autism is a neurodevelopmental condition defined on clinical criteria related to diminished social reciprocity and stereotyped behavior. An influential view explains autism as a social motivation disorder characterized by less attention paid to the social environment and less pleasure experienced with social rewards. However, experimental attempts to validate this theory, by testing the impact of social reward on behavioral choice and brain activity, has yielded mixed results, possibly due to variations in how explicit instructions were about task goals. Here, we specified the putative motivation deficit as an absence of spontaneous valuation in the social domain, unexplained by inattention and correctible by explicit instruction. Since such deficit cannot be assessed with behavioral measures, we used functional neuroimaging (fMRI) to readout covert subjective values, assigned to social and nonsocial stimuli (faces and objects), either explicitly asked to participants (during a likeability judgment task) or not (during age or size estimation tasks). Value-related neural activity observed for objects, or for faces under explicit instructions, was very similar in autistic and control participants, with an activation peak in the ventromedial prefrontal cortex (vmPFC), known as a key node of the brain valuation system. The only difference observed in autistic participants was an absence of the spontaneous valuation normally triggered by faces, even when they were attended for age estimation. Our findings, therefore, suggest that in autism, social stimuli might fail to trigger the automatic activation of the brain valuation system.

自闭症是一种根据与社会互惠减少和刻板行为相关的临床标准定义的神经发育状况。一个有影响力的观点将自闭症解释为一种社会动机障碍，其特征是对社会环境的关注较少，对社会奖励的愉悦感较少。然而，通过测试社会奖励对行为选择和大脑活动的影响来验证这一理论的实验尝试产生了不同的结果，这可能是由于关于任务目标的明确指令的变化。在这里，我们将推定的动机缺陷指定为社会领域中缺乏自发的评价，无法通过疏忽来解释，并且可以通过明确的指导来纠正。由于这种缺陷不能用行为测量来评估，我们使用功能性神经影像学 (fMRI) 来读出分配给社会和非社会刺激（面部和物体）的隐蔽主观值，明确要求参与者（在喜好判断任务期间）或不明确要求（在年龄或尺寸估计任务期间）。观察到的物体或明确指示下的面部的价值相关神经活动在自闭症和控制参与者中非常相似，腹内侧前额叶皮层 (vmPFC) 中的激活峰值被称为大脑评估系统的关键节点。在自闭症参与者中观察到的唯一差异是缺乏通常由面孔触发的自发评估，即使他们参加年龄估计也是如此。因此，我们的研究结果表明，在自闭症中，社会刺激可能无法触发大脑评估系统的自动激活。