Systems Neuroscience of Primate Social Cognition

人类和其他灵长类动物的大脑是用来处理社会信息的。从出生的那一刻起，我们的社会伙伴就抓住了我们的兴趣。观察他人不仅可以帮助我们优化自己的决定（“社会学习”），还可以帮助我们了解伴侣的想法，并预测他们的意图和行为（“心理化”）。这些社会认知能力在自闭症、社交焦虑、精神分裂症和相关的人类疾病中受到严重损害，这是由于特定大脑回路的功能障碍。然而，我们对这些大脑回路中的神经元如何处理信息以实现社会认知和社会互动知之甚少。这是一个重要的问题，因为神经元是大脑中交换信息的基本计算元素。为了理解类人社会认知及其障碍，我们需要知道神经元和分布式大脑系统如何在社会互动中处理信息。我们通过记录猴子在解决奖励导向和基于规则的决策问题时大脑特定部位单个神经元的活动来解决这个问题。记录动物在社会互动环境中执行这些决策任务时的神经元活动，使我们能够解决具体问题：当猴子观察并从彼此的选择中学习时，神经元是如何处理社会伙伴选择选项的价值的？具体来说，神经元是否从伴侣独特的主观角度来处理这种奖励价值，即使这种角度与自己的不同？这个过程，被称为心智化，在自闭症中严重受损。此外，当猴子在认知问题解决任务中相互作用学习抽象规则时，神经元是否会根据观察到的伙伴的选择更新对当前有效规则的预期？他们是否会追踪对方对当前有效规则的看法，即使这种看法与自己的看法不同？在研究了这些任务中的神经元活动之后，我们还在任务执行过程中可逆地干扰了特定的大脑区域，这将有助于我们了解哪些大脑区域对社会认知做出了重要贡献。最后，基于获得的数据，我们将建立我们所研究的大脑回路的计算机模型，以更好地理解这些大脑区域的信息处理机制和计算。我们关注的是杏仁核和部分前额皮质等大脑区域，我们已经知道它们在人类社会认知障碍中起着重要作用。我们之所以在这项研究中使用猴子，是因为它们具有与人类相近的复杂社交能力，而且它们适合记录单个神经元的活动。尽管人类大脑成像可以帮助识别大脑的哪些区域参与社会认知，但成像信号太慢，空间上不精确，无法揭示单个神经元中动态的、毫秒级的信息流。同样，尽管对啮齿动物的研究可以揭示基本社会行为（如攻击和交配）的神经机制，但它们无法研究高级的、人类典型的社会认知，如社会规则学习、换位思考和心理化。

The brains of humans and other primates are tuned for social information. From the moment of birth, our social partners capture our interest. Observing others not only helps us optimise our own decisions ('social learning'), but also helps us understand our partners' minds and predict their intentions and behaviour ('mentalizing'). These social-cognitive abilities are profoundly impaired in autism, social anxiety, schizophrenia and related human conditions, due to dysfunction of specific brain circuits. Yet, we know very little about how neurons in these brain circuits process information to enable social cognition and social interactions. This is an important question because neurons are the basic computing elements of the brain that exchange information.To understand human-like social cognition and its disorders, we need to know how neurons and distributed brain systems process information during social interactions. We address this issue by recording the activity of individual neurons in specific parts of the brain while monkeys socially interact with each other to solve reward-guided and rule-based decision problems.Recording neuronal activity while the animals perform these decision tasks in a social, interactive context allows us to address specific questions: When monkeys observe and learn from each other's choices, how do neurons process the value of the social partner's choice options? Specifically, do neurons process such reward values from the partner's unique subjective perspective, even when this perspective differs from one's own? This process, known as mentalizing, is profoundly impaired in autism. Further, when monkeys interact to learn about abstract rules in a cognitive problem-solving task, do neurons update expectations about which rule is currently valid based on the observed partner's choices? And do they track the partner's belief about which rule is currently valid, even when this belief is different to one's own belief?After studying the neuronal activity in these tasks, we also reversibly interfere with specific brain areas during task performance, which will help us understand which brain areas make essential contributions to social cognition. Finally, based on the obtained data, we will build computer models of the brain circuits we study, to better understand the information-processing mechanisms and computations performed in these brain areas. We focus on brain areas such as the amygdala and parts of prefrontal cortex, which we already know play a role in human social-cognition disorders.We use monkeys in this research because they have sophisticated social abilities close to those of humans, and because they are suitable for recording the activity of individual neurons. Although human brain imaging can help identify which areas of the brain participate in social cognition, the imaging signal is too slow and spatially imprecise to reveal the dynamic, millisecond-precise information flow in single neurons. Likewise, although studies in rodents can uncover neuronal mechanisms for basic social behaviours such as aggression and mating, they cannot investigate advanced, human-typical social cognition such as social rule-learning, perspective-taking and mentalizing.