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

摘要 自拉蒙·伊·卡哈尔以来，神经学家一直推测，即使是最复杂的大脑功能也可能- 实际上是在神经细胞类型及其连接的水平上理解的。最近，虽然我们已经- 为了了解啮齿动物大脑皮质回路中的细胞类型及其连接原理，我们在 在细胞类型及其联系的水平上了解灵长类皮质的回路组织， 延缓了对原始人复杂认知能力的电路水平机械理解的进展 伙计们。例如，人类大脑皮层有两种独特的形态类型，即von Economo神经元(VENS)和 叉状细胞，集中在皮质区域，支持复杂的社会认知能力和自我 意识。很长一段时间以来，文氏和叉状细胞被认为是人类和类人猿所独有的，并且 因此，被假设为意识和类似人类的复杂社会行为的神经关联。 尽管它们很重要，但它们的功能被认为是实验上难以处理的，因为它们只有 对原始人的限制。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 也存在于猕猴的前脑岛(AI)，为 在实验室中对这些新神经元的功能进行表征。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- 在中国的测序(scRNA-seq)中，我们建议以此为契机剖析MON-SEQ的大脑皮层回路。 关键人工智能，并从电生理学、形态学、转录组和 连通性。通过利用一套新的经济高效、高吞吐量的方法，包括大型 基于水滴的scRNA-seq、Patch-seq和多细胞斑片记录，我们的目标是识别和表征- 对组成猴子AI的所有细胞类型进行分子、空间和功能注释。尤其是， 这种对猕猴皮质回路的全面询问将导致详细的、功能特征 文斯和FCS的第一次。重要的是，通过补充两家公司的实力和独特资源 在美国和中国的合作实验室，我们希望完成这一原本不可行、成本高昂的灵长类动物再研究 在合理的预算和时间段内进行这种规模的搜索，提供前所未有的知识和重新 为了解该领域出现的类人类社会智力和相关的神经精神病学提供素材 精神错乱。特别是，识别这些新细胞类型的特定标记基因将促进该领域 开发有基因针对性的工具，在行为背景下研究类似人类的社会认知能力。 有了所有可用的信息和工具，我们对人类智力的理解，以前被认为是前- 在很大程度上是顽固的和投机的，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.