研究人类大脑皮层宏观连通性的功能和结构研究表明,与主要区域相比,高阶关联区域表现出更大的连通性。然而,这些大脑区域的突触组织仍未被探索。在目前的工作中,我们进行了体积电子显微镜来研究尸检时获得的人脑突触组织。具体来说,我们检查了布罗德曼区17、3b的第三层,和4,作为初级视觉的代表性区域,躯体感觉,和运动皮层。此外,我们与以前的颞极和前扣带回相关皮质区域(Brodmann区域24,38和21)的第III层数据集进行了比较分析.对9,690个突触连接进行了三维重建,表明某些突触特征特定于特定区域。每个体积的突触数量,突触后靶标的比例,突触大小可以区分一个区域和另一个区域,不管它们是联想皮层还是初级皮层。相比之下,其他突触特征是所有分析区域共有的,例如兴奋性和抑制性突触的比例,它们的形状,它们的空间分布,位于树突棘上的突触比例更高。本结果为人类大脑皮层的突触组织提供了进一步的见解。
Functional and structural studies investigating macroscopic connectivity in the human cerebral cortex suggest that high-order associative regions exhibit greater connectivity compared to primary ones. However, the synaptic organization of these brain regions remains unexplored. In the present work, we conducted volume electron microscopy to investigate the synaptic organization of the human brain obtained at autopsy. Specifically, we examined layer III of Brodmann areas 17, 3b, and 4, as representative areas of primary visual, somatosensorial, and motor cortex. Additionally, we conducted comparative analyses with our previous datasets of layer III from temporopolar and anterior cingulate associative cortical regions (Brodmann areas 24, 38, and 21). 9,690 synaptic junctions were 3D reconstructed, showing that certain synaptic characteristics are specific to particular regions. The number of synapses per volume, the proportion of the postsynaptic targets, and the synaptic size may distinguish one region from another, regardless of whether they are associative or primary cortex. By contrast, other synaptic characteristics were common to all analyzed regions, such as the proportion of excitatory and inhibitory synapses, their shapes, their spatial distribution, and a higher proportion of synapses located on dendritic spines. The present results provide further insights into the synaptic organization of the human cerebral cortex.