Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223 Madrid, Spain.
Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Doctor Arce 37, 28002 Madrid, Spain.
Cereb Cortex. 2023 Aug 23;33(17):9691-9708. doi: 10.1093/cercor/bhad232.
The human anterior cingulate and temporopolar cortices have been proposed as highly connected nodes involved in high-order cognitive functions, but their synaptic organization is still basically unknown due to the difficulties involved in studying the human brain. Using Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) to study the synaptic organization of the human brain obtained with a short post-mortem delay allows excellent results to be obtained. We have used this technology to analyze layer III of the anterior cingulate cortex (Brodmann area 24) and the temporopolar cortex, including the temporal pole (Brodmann area 38 ventral and dorsal) and anterior middle temporal gyrus (Brodmann area 21). Our results, based on 6695 synaptic junctions fully reconstructed in 3D, revealed that Brodmann areas 24, 21 and ventral area 38 showed similar synaptic density and synaptic size, whereas dorsal area 38 displayed the highest synaptic density and the smallest synaptic size. However, the proportion of the different types of synapses (excitatory and inhibitory), the postsynaptic targets, and the shapes of excitatory and inhibitory synapses were similar, regardless of the region examined. These observations indicate that certain aspects of the synaptic organization are rather homogeneous, whereas others show specific variations across cortical regions.
人类的前扣带皮质和颞极皮质被认为是参与高级认知功能的高度连接节点，但由于研究人类大脑的困难，其突触组织仍然基本未知。使用聚焦离子束/扫描电子显微镜（FIB/SEM）研究具有短死后延迟获得的人脑的突触组织可以获得出色的结果。我们使用这项技术分析了前扣带皮质（Brodmann 区域 24）的第 III 层和颞极皮质，包括颞极（Brodmann 区域 38 腹侧和背侧）和前中颞回（Brodmann 区域 21）。我们的结果基于在 3D 中完全重建的 6695 个突触连接，表明 Brodmann 区域 24、21 和腹侧区域 38 具有相似的突触密度和突触大小，而背侧区域 38 则显示出最高的突触密度和最小的突触大小。然而，不同类型的突触（兴奋性和抑制性）、突触后靶标以及兴奋性和抑制性突触的形状的比例在不同区域之间是相似的。这些观察结果表明，突触组织的某些方面相当均匀，而其他方面则在皮质区域之间表现出特定的变化。
