The human cerebral cortex houses 1,000 times more neurons than the cerebral cortex of a mouse, but the possible differences in synaptic circuits between these species are still poorly understood. We used 3-dimensional electron microscopy of mouse, macaque and human cortical samples to study their cell type composition and synaptic circuit architecture. The 2.5-fold increase in interneurons in humans compared to mouse was compensated by a change in axonal connection probabilities and therefore did not yield a commensurate increase in inhibitory-vs-excitatory synaptic input balance on human pyramidal cells. Rather, increased inhibition created an expanded interneuron-to-interneuron network, driven by an expansion of interneuron-targeting interneuron types and an increase in their synaptic selectivity for interneuron innervation. These constitute key neuronal network alterations in human cortex.

中文翻译：

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小鼠和人类皮层的连接组学比较

人类大脑皮层的神经元数量是小鼠大脑皮层的 1000 倍，但这些物种之间突触回路的可能差异仍然知之甚少。我们使用小鼠、猕猴和人类皮质样本的 3 维电子显微镜来研究它们的细胞类型组成和突触电路结构。与小鼠相比，人类中间神经元增加了 2.5 倍，这被轴突连接概率的变化所补偿，因此人类锥体细胞的抑制性与兴奋性突触输入平衡没有产生相应的增加。相反，增加的抑制创建了一个扩展的中间神经元到中间神经元网络，这是由中间神经元靶向中间神经元类型的扩展和它们对中间神经元神经支配的突触选择性的增加驱动的。