Deciphering the transcriptomic signatures, physiology, and connectivity of the specialized morphotypes in macaque insular cortex

摘要 自拉蒙·卡哈尔以来，神经科学家推测，即使是最复杂的大脑功能也可能—— 最终可以在神经元细胞类型及其连接的水平上进行理解。最近，虽然我们已经- 为了了解啮齿动物皮层回路中的细胞类型及其接线原理，我们仍处于婴儿期 了解灵长类皮质在细胞类型及其连接水平上的电路组织， 减缓对初级复杂认知能力的电路级机械理解的进展 伙伴们。例如，人类皮层有两种独特的形态类型：冯·伊科诺莫神经元 (VEN) 和 叉细胞，集中在支持复杂的社会认知能力和自我认知能力的皮质区域 意识。长期以来，VEN 和叉细胞被认为是人类和类人猿所独有的，并且 因此被假设为意识和类人复杂社会行为的神经关联。 尽管它们很重要，但鉴于它们的排他性，它们的功能被认为在实验上很难处理。 对原始人的严格限制。然而，最近的一项研究提供了令人信服的证据，证明这些独特的形态类型 也存在于猕猴的前岛叶（AI）中，为 在实验室中对这些新型神经元的功能表征。在这里，通过与中国灵长类动物合作 研究实验室利用丰富的猕猴资源和较低的单细胞RNA成本 测序（scRNA-seq）在中国，我们建议借此机会解剖单核细胞的皮质回路 关键人工智能，并在电生理学、形态学、转录组等方面表征这些新型细胞类型 连接性。通过利用一套新颖的、具有成本效益的、高通量的方法，包括大规模 规模基于液滴的 scRNA-seq、Patch-seq 和多细胞 patch 记录，我们的目标是识别和表征 对构成猴 AI 的所有细胞类型进行分子、空间和功能注释。特别是， 对猕猴皮层回路的全面询问将导致详细的功能表征 首次引入 VEN 和 FC。重要的是，通过互补两家公司的实力和独特资源 通过与美国和中国的实验室合作，我们期望完成这项原本不可行、成本高昂的灵长类动物研究 在合理的预算和时间段内进行如此规模的搜索，提供了前所未有的知识和重新 该领域了解类人社交智能和相关神经精神病学的出现的来源 失调。特别是，鉴定这些新细胞类型的特定标记基因将促进该领域的发展 开发基因靶向工具来研究行为背景下的类人社会认知能力。 有了所有可用的信息和工具，我们对人类智能的理解，以前被认为是前 暂时难以处理且很大程度上是投机性的，最终将获得坚实的基础并准备在 不久的将来。

Abstract Since Ramon y Cajal, neuroscientists have speculated that even the most complex brain functions might even- tually be understood at the level of neuronal cell types and their connections. More recently, while we have be- gun to understand cell types and their wiring principles in cortical circuits of rodents, we are still in infancy in understanding the circuit organization of the primate cortex at the level of cell types and their connections, slowing progress toward a circuit-level mechanistic understanding of complex cognitive capabilities of pri- mates. For instance, the human cortex houses two unique morphotypes, von Economo neurons (VENs) and fork cells, which are concentrated in the cortical regions that support complex social cognitive abilities and self- awareness. For a long time, the VENs and fork cells are believed to be unique to human and great apes, and thus are hypothesized to be the neural correlate of consciousness and human-like complex social behaviors. Despite their importance, their functions are deemed to be experimentally intractable given their exclusive re- striction to hominids. A recent study, however, provides compelling evidence that these unique morphotypes are also present in the anterior insula (AI) of macaque monkeys, providing an unprecedented opportunity for functional characterization of these novel neurons in the laboratory. Here, by partnering with a Chinese primate research laboratory to leverage the abundant macaque resources and lower cost of single-cell RNA- sequencing (scRNA-seq) in China, we propose to take this opportunity to dissect out the cortical circuit of mon- key AI and characterize these novel cell types in terms of electrophysiology, morphology, transcriptome, and connectivity. By taking advantage of a novel set of cost-effective, high-throughput approaches, including large- scale droplet-based scRNA-seq, Patch-seq, and multi-cell patch recordings, we aim to identify and character- ize all the cell types that comprise monkey AI with molecular, spatial and functional annotations. Particularly, this comprehensive interrogation of macaque cortical circuit will lead to a detailed, functional characterization of VENs and FCs for the first time. Importantly, by complementing the strength and unique resources of two collaborating labs in USA and in China, we expect to accomplish this otherwise infeasible, costly primate re- search at this scale within a reasonable budget and time period, providing unprecedented knowledge and re- source for the field to understand the emergence of human-like social intelligence and related neuropsychiatric disorders. Particularly, identifying the specific marker genes for those novel cell types will promote the field to develop genetically targeted tools for studying human-like social cognitive abilities in the context of behaviors. With all information and tools available, our understanding of human intelligence, previously perceived as ex- perimentally intractable and largely speculative, will finally gain solid ground and are ready to take off in the near future.