In the present study we have used Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) to perform a study of the synaptic organization of layer III of Brodmann's area 21 in human. We analyzed the synaptic density, 3D spatial distribution, and type (excitatory/inhibitory), as well as the shape and size of each synaptic junction of 4945 synapses that were fully reconstructed in 3D. Moreover, the postsynaptic targets of 1888 synapses were determined. We also compared several electron microscopy methods and analysis tools to estimate the synaptic density in the same brain tissue. We have shown that FIB/SEM is much more reliable and robust than the majority of the other commonly used EM techniques. The present work constitutes a detailed description of the synaptic organization of cortical layer III. Further studies on the rest of the cortical layers are necessary to better understand the functional organization of this temporal cortical region.

中文翻译：

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人类颞新皮层第三层的三维突触组织

在本研究中，我们已使用聚焦离子束/扫描电子显微镜（FIB / SEM）对人Brodmann区域21的第III层的突触组织进行了研究。我们分析了4945个突触的突触密度，3D空间分布和类型（兴奋性/抑制性），以及每个突触连接的形状和大小，这些突触在3D中完全重建。此外，确定了1888个突触的突触后目标。我们还比较了几种电子显微镜方法和分析工具，以估计同一大脑组织中的突触密度。我们已经证明，FIB / SEM比大多数其他常用的EM技术更加可靠和健壮。本工作构成了皮质第三层的突触组织的详细描述。