Division of Behavioral Development, Department of System Neuroscience, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8585, Japan.
Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies, Hayama, Kanagawa 240-0193, Japan.
Proc Natl Acad Sci U S A. 2024 Jul 30;121(31):e2403445121. doi: 10.1073/pnas.2403445121. Epub 2024 Jul 24.
Modulation of neuronal firing rates by the spatial locations of physical objects is a widespread phenomenon in the brain. However, little is known about how neuronal responses to the actions of biological entities are spatially tuned and whether such spatially tuned responses are affected by social contexts. These issues are of key importance for understanding the neural basis of embodied social cognition, such as imitation and perspective-taking. Here, we show that spatial representation of actions can be dynamically changed depending on others' social relevance and agents of action. Monkeys performed a turn-taking choice task with a real monkey partner sitting face-to-face or a filmed partner in prerecorded videos. Three rectangular buttons (left, center, and right) were positioned in front of the subject and partner as their choice targets. We recorded from single neurons in two frontal nodes in the social brain, the ventral premotor cortex (PMv) and the medial prefrontal cortex (MPFC). When the partner was filmed rather than real, spatial preference for partner-actions was markedly diminished in MPFC, but not PMv, neurons. This social context-dependent modulation in the MPFC was also evident for self-actions. Strikingly, a subset of neurons in both areas switched their spatial preference between self-actions and partner-actions in a diametrically opposite manner. This observation suggests that these cortical areas are associated with coordinate transformation in ways consistent with an actor-centered perspective-taking coding scheme. The PMv may subserve such functions in context-independent manners, whereas the MPFC may do so primarily in social contexts.
物理对象的空间位置对神经元发放率的调制是大脑中的一种普遍现象。然而，对于生物实体的动作如何在空间上被神经元响应以及这种空间调谐的响应是否受到社会环境的影响，我们知之甚少。这些问题对于理解具身社会认知的神经基础（如模仿和换位思考）至关重要。在这里，我们表明，动作的空间表示可以根据他人的社会相关性和动作的执行者而动态改变。猴子与面对面的真实猴子伙伴或预先录制的视频中的虚拟伙伴进行轮流选择任务。三个矩形按钮（左、中、右）被放置在主体和伙伴的前面作为他们的选择目标。我们记录了来自社会大脑中两个额叶节点（腹侧前运动皮层[PMv]和内侧前额叶皮层[MPFC]）的单个神经元的活动。当伙伴是虚拟的而不是真实的时，MPFC 中的神经元对伙伴动作的空间偏好明显减弱，但 PMv 中的神经元没有。这种在 MPFC 中与社会环境相关的调制也表现在自我动作中。引人注目的是，这两个区域的一部分神经元以截然相反的方式在自我动作和伙伴动作之间切换了它们的空间偏好。这一观察结果表明，这些皮质区域与以行为者为中心的换位思考编码方案一致，在坐标转换中起着作用。PMv 可能以独立于上下文的方式执行这种功能，而 MPFC 可能主要在社会环境中执行这种功能。
