A connectome is a comprehensive map of neural connections of a species nervous system. While recent work has begun comparing connectomes across a wide breadth of species, we present here a more detailed and specific comparison of connectomes across the primate order. Long-range connections are thought to improve communication efficiency and thus brain function but are costly in terms of energy and space utilization. Methods for measuring connectivity in the brain include measuring white matter volume, histological cell counting, anatomical tract tracing, diffusion-weighted imaging and tractography, and functional connectivity in MRI. Comparisons of global white matter connectivity suggest that larger primate brains are less well connected than smaller primate brains, but that humans have more connections than expected for our cortical neuron number, which may be concentrated in the prefrontal cortex. Although there is significant overlap in structural connectivity between humans and nonhuman primates, human-specific connections are found in cortical areas involved with language, imitation, and tool use. Similar to structural connectivity, there is also widespread overlap between humans and macaques in resting state functional connectivity. However, there are again a number of human-specific connections in cortical regions involved in language, tool use, and empathy. Comparative connectomics also offers the opportunity to detect specializations of connectivity in other primate species besides humans. Future research should capitalize on the ability of diffusion tractography to measure connectivity in postmortem brains that could expand the representation of species beyond humans, chimpanzees, and rhesus macaques, and facilitate identification of connectivity-based adaptations to different social and ecological niches. This work will require careful attention to establishing cortical homologies across species and to improving tractography methods to limit detection of false-positive and false-negative connections. Finally, it will be important to attempt to establish the functional significance of variation in connectivity profiles by examining how these covary with behavior and cognition both across and within species.

中文翻译：

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比较灵长类连接组学。

连接组是物种神经系统神经连接的综合图。尽管最近的工作已开始比较各种物种的连接体，但我们在此展示了灵长类中连接体的更详细和具体的比较。远程连接被认为可以提高通信效率，从而改善大脑功能，但在能源和空间利用方面却很昂贵。衡量大脑中连通性的方法包括测量白质体积，组织细胞计数，解剖道追踪，弥散加权成像和影像学检查以及MRI中的功能连通性。全球白质连通性的比较表明，大型灵长类动物的大脑比小型灵长类动物的大脑连接性差，但是人类与我们的皮层神经元数量的联系比预期的要多，这可能集中在前额叶皮层。尽管人类和非人类灵长类动物在结构上的连接存在大量重叠，但是在涉及语言，模仿和工具使用的皮质区域中发现了特定于人类的连接。类似于结构连接，人类和猕猴在静止状态功能连接中也存在广泛的重叠。但是，在大脑皮层区域中，在语言，工具使用和同理心方面仍然存在许多特定于人类的连接。比较连接组学还提供了机会来检测人类以外其他灵长类物种的连接专长。未来的研究应利用扩散束线照相术测量死后大脑中的连通性的能力，这可以将物种的代表范围扩展到人类，黑猩猩和恒河猴之外，并有助于识别基于连通性的适应不同社会和生态环境的适应性。这项工作将需要仔细注意，以建立跨物种的皮质同源性，并改善束线照相法以限制对假阳性和假阴性连接的检测。最后，通过检查物种与物种之间以及物种内部与行为和认知的关系如何，试图建立连通性分布变化的功能意义将非常重要。并帮助确定基于连通性的适应方式，以适应不同的社会和生态环境。这项工作将需要仔细注意，以建立跨物种的皮质同源性，并改善束线照相法以限制对假阳性和假阴性连接的检测。最后，通过检查物种与物种之间以及物种内部与行为和认知的关系如何，试图建立连通性分布变化的功能意义将非常重要。并帮助确定基于连通性的适应方式，以适应不同的社会和生态环境。这项工作将需要仔细注意，以建立跨物种的皮质同源性，并改善束线照相法以限制对假阳性和假阴性连接的检测。最后，通过检查物种与物种之间以及物种内部与行为和认知的关系如何，试图建立连通性分布变化的功能意义将非常重要。