北大神经生物学—4中枢神经系统发育及其可塑性.ppt

* * * * * - Inside-out development of the cortex - the first cells to migrate to cortical plate from VZ that form subplate - As these differentiate into neurons – become layer VI in the cortical plate. - this process repeats again and again until all layers of the cortex – the sublate neurons disappear 较早分化的较大神经元先迁移并形成最内层，依次顺序向外；而较晚分化的较小神经元则通过已形成的层次迁移并形成其外侧新的层次；故不论皮质的什么区域，其最内层总是最早分化，而最外层则最后分化。 哺乳动物大脑新皮层功能区域的形成 （A）在正常发育过程中，胚胎前脑背部中线和头端的成型中心分泌BMP、Wnt和FGF8等因子，使这些蛋白分别沿背腹轴和前后轴形成浓度梯度，进而影响多种转录因子在神经前期细胞中的表达量，最终把大脑新皮层分化成不同的功能区域。 （B）受在胚胎前脑后端异位表达的FGF8影响，大脑新皮层能在后端形成第二个运动和躯体感觉皮层。 3. Cell differentiation The process in which a cell take on the appearance and characteristics of a neuron is known as cell differentiation. Differentiation is the consequence of a specific spatiotemporal pattern of gene expression. Differentiation of the neuroblast into a neuron begins with the appearance of neurites sprouting off the body (all same – axon and dendrite at first). The differentiation is programmed well before the neuroblast arrives at its final resting place. The complexity of dendritic tree is not entirely preprogrammed. The fine structure of axons and dendrites also depends on “environmental” factors in the cortex. 3.1 Differentiation of cortical areas Niss-stained position of the major vibrissae on the face vibrissae region of S1 Barrels in S1 - A somatotopic map of the facial vibrissae on mouse cerebral cortex 在决定神经细胞命运的过程中，细胞之间的相互作用起重要作用。这些相互作用既可以发生于神经细胞与非神经细胞之间，也可以发生于神经细胞之间；这些相互作用既可以通过弥散在环境中的诱导因子，也能通过细胞之间的直接对话。 细胞外的因子最终会在细胞内激活一个特异的分裂和分化程序，使神经前体细胞可以在很大程度上不受环境的影响，产生不同的神经细胞。通过对这些机理的进一步的研究，发育神经生物学的最终目标是能够精确地描述：在发育过程中，不同的神经元和胶质细胞如何按准确的数量、在特定的时期、在不同的神经系统部位产生。 ? Genesis of connection / synapse formation LM: Model (chemical synapse ) Review：definition, classify, structure EM: Genesis of connection: for example 1. The three phases of pathway formation Pathway selection – path target selection – structure address selection – cell The three phases depends on : Di