Supèr H, Uylings H B
Graduate School of Neurosciences Amsterdam, Department of Visual System Analysis, AMC, University of Amsterdam, PO Box 12011, 1100 AA Amsterdam, The Netherlands.
Cereb Cortex. 2001 Dec;11(12):1101-9. doi: 10.1093/cercor/11.12.1101.
During development, a cerebral cortex appears in the wall of the telencephalic vesicle in reptiles and mammals. It arises from a cell-dense cortical plate, which develops within a primordial preplate. The neurons of the preplate are essential for cortical development; they regulate the neuronal migration of the cortical plate neurons and form the first axonal connections. In the reptilian cortex and in the hippocampus of the mammalian cerebral cortex, most ingrowing afferent axons run above the cortical plate, in the zone where the receptive tufts of apical dendrites of the cortical pyramidal neurons branch extensively. In the mammalian neocortex, however, axons enter mainly from below the cortical plate where they do not encounter the apical tufts of these pyramidal neurons. In this paper, we discuss the idea that this difference in cortical development has relieved a functional constraint in the expansion of the cortex during evolution. We hypothesize that the entrance of axons below the cell-dense cortical plate, together with the inside-out migration of cortical neurons, ensures that the neocortex remains an "open" system, able to differentiate into new (sub)layers and more cortical areas.
在发育过程中，爬行动物和哺乳动物的端脑泡壁上会出现大脑皮层。它起源于一个细胞密集的皮质板，该皮质板在原始前板内发育。前板中的神经元对皮层发育至关重要；它们调节皮质板神经元的神经元迁移并形成最初的轴突连接。在爬行动物的皮层和哺乳动物大脑皮层的海马体中，大多数向内生长的传入轴突在皮质板上方运行，即在皮质锥体细胞顶端树突的感受性簇广泛分支的区域。然而，在哺乳动物的新皮层中，轴突主要从皮质板下方进入，在那里它们不会遇到这些锥体细胞的顶端簇。在本文中，我们讨论了这样一种观点，即皮层发育中的这种差异在进化过程中减轻了皮层扩张的功能限制。我们假设轴突在细胞密集的皮质板下方进入，再加上皮质神经元由内向外的迁移，确保新皮层仍然是一个“开放”系统，能够分化出新的（亚）层和更多的皮质区域。
