University of Oxford, Department of Physiology, Anatomy and Genetics, Le Gros Clark Building, South Parks Road, Oxford OX1 3QX, UK.
Eur J Neurosci. 2012 May;35(10):1573-85. doi: 10.1111/j.1460-9568.2012.08119.x.
Thalamocortical axons must cross a complex cellular terrain through the developing forebrain, and this terrain has to be understood for us to learn how thalamocortical axons reach their destinations. Selective fasciculation, guidepost cells and various diencephalic and telencephalic gradients have been implicated in thalamocortical guidance. As our understanding of the relevant forebrain patterns has increased, so has our knowledge of the guidance mechanisms. Our aim here is to review recent observations of cellular and molecular mechanisms related to: the growth of thalamofugal projections to the ventral telencephalon, thalamic axon avoidance of the hypothalamus and extension into the telencephalon to form the internal capsule, the crossing of the pallial-subpallial boundary, and the growth towards the cerebral cortex. We shall review current theories for the explanation of the maintenance and alteration of topographic order in the thalamocortical projections to the cortex. It is now increasingly clear that several mechanisms are involved at different stages of thalamocortical development, and each contributes substantially to the eventual outcome. Revealing the molecular and cellular mechanisms can help to link specific genes to details of actual developmental mechanisms.
丘脑皮质轴突必须穿过发育中的前脑的复杂细胞地形，为了了解丘脑皮质轴突如何到达目的地，我们必须了解这个地形。选择性聚集、引导细胞以及各种间脑和端脑梯度已被牵涉到丘脑皮质导向中。随着我们对相关前脑模式的理解的增加，我们对导向机制的了解也在增加。我们在这里的目的是回顾与以下方面相关的细胞和分子机制的最新观察结果：丘脑投射纤维向腹侧端脑的生长、丘脑轴突避免下丘脑并延伸到端脑形成内囊、皮层-下皮层边界的穿越以及向大脑皮层的生长。我们将回顾目前解释丘脑皮质投射到皮质的拓扑顺序的维持和改变的理论。现在越来越清楚的是，几个机制在丘脑皮质发育的不同阶段都有涉及，并且每个机制都对最终结果做出了重要贡献。揭示分子和细胞机制可以帮助将特定基因与实际发育机制的细节联系起来。
