Chivukula Srinivas, Aflalo Tyson, Zhang Carey, Rosario Emily R, Bari Ausaf, Pouratian Nader, Andersen Richard A
Department of Neurological Surgery, UT Southwestern Medical Center, Dallas, TX 75390.
Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125.
Proc Natl Acad Sci U S A. 2025 Jan 7;122(1):e2316012121. doi: 10.1073/pnas.2316012121. Epub 2024 Dec 30.
Cognition relies on transforming sensory inputs into a generalizable understanding of the world. Mirror neurons have been proposed to underlie this process, mapping visual representations of others' actions and sensations onto neurons that mediate our own, providing a conduit for understanding. However, this theory has limitations. Here, we hypothesize that mirror-like responses represent one facet of a broader framework in which our brains engage internal models for cognition. We recorded populations of single neurons in the human posterior parietal cortex (PPC) of a brain-machine interface clinical trial participant implanted with a microelectrode array while she either experienced actual touch, or observed diverse tactile stimuli applied to other individuals. Two body locations were tested, on each of the participant and other individuals. Some neurons exhibited mirror-like properties, consistent with earlier literature. However, they were fragile, breaking with increased task complexity. Population responses were better characterized by generalizable and compositional basic-level features encoded within neural subspaces. These features enable the population to respond to diverse actual and observed touch stimuli and are recruited similarly for similar forms of touch. Mirror-like neurons belong within these subspaces, contributing more globally to compositionality and generalizability. We speculate that at a population-level, human PPC manifests an internal model for touch, and that cognition unfolds in the high-level human cortex by versatility in its representational building blocks. In a broad sense, we speculate that the population features we demonstrate support a broad mechanism by which the high-level human cortex enables understanding.
认知依赖于将感官输入转化为对世界的可概括理解。有人提出镜像神经元是这一过程的基础，将他人动作和感觉的视觉表征映射到介导我们自身动作和感觉的神经元上，提供了一种理解的途径。然而，这一理论存在局限性。在此，我们假设类似镜像的反应代表了一个更广泛框架的一个方面，在这个框架中我们的大脑运用内部模型进行认知。在一项脑机接口临床试验中，我们记录了一名植入微电极阵列的参与者大脑后顶叶皮层（PPC）中的单个神经元群体活动，该参与者要么体验实际的触摸，要么观察施加于其他人的各种触觉刺激。对参与者和其他人的两个身体部位进行了测试。一些神经元表现出类似镜像的特性，与早期文献一致。然而，它们很脆弱，随着任务复杂性的增加而消失。群体反应更能通过神经子空间中编码的可概括和组合的基本水平特征来表征。这些特征使群体能够对各种实际和观察到的触摸刺激做出反应，并且在类似形式的触摸中以类似方式被激活。类似镜像的神经元属于这些子空间，对组合性和可概括性做出更全局的贡献。我们推测在群体水平上，人类PPC表现出一种触摸的内部模型，并且认知在人类高级皮层中通过其表征构建块的通用性而展开。从广义上讲，我们推测我们所展示的群体特征支持了一种广泛的机制，通过这种机制人类高级皮层实现理解。
