A model for the formation of ocular dominance stripes
A model for the formation of ocular dominance stripes
复制标题
眼优势条纹形成的模型
DOI：
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发表时间：
1980
期刊：
影响因子：
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通讯作者：
N. Swindale
中科院分区：
文献类型：
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作者：
N. Swindale
本文描述了一个竞争模型，解释了猫和猴视觉皮层IVc层中眼优势条纹的形成。主要的假设是，突触对其他突触的生长产生影响，并且这些影响延伸到至少600 μm的距离，并且在该距离内的大小和符号不同。相似类型的突触之间的相互作用被认为是刺激的距离高达约200 μm，和抑制的距离为200-600 μm。相反的情况也适用于对侧眼型突触之间的相互作用，在200 μm以下的距离上，这种作用是抑制性的，而在更长的距离上，这种作用是刺激性的。假设相互作用是圆对称的。因此，例如右眼突触在一个点处的生长将（a）促进右眼突触的局部生长并抑制左眼突触的局部生长，以及（B）在围绕初始增加点的环形环中促进左眼突触的生长并抑制右眼突触的生长。在发育开始时，右眼和左眼突触被认为是在IVc层内随机混合的。计算机模拟表明，结合这些假设的各种条件将导致条纹图案的形成。这些复制了猴子眼优势条纹的许多形态学特征，包括Y型和型分支和终止，条纹以直角进入图案边界的趋势，以及在分支点变窄的趋势。该模型可以解释单眼剥夺条纹形态的影响，如果它被假定为剥夺眼突触在确定本地增长率的有效性降低。如果假设末梢的横向生长不会发生，并且当突触密度接近最大值时，某些因素（如突触后位点的有限可用性）降低了突触的生长速率，则可以解释这些效应的临界期的存在。该模型可以推广到其他系统中的图案形成，如斑马或鲭鱼皮，其中出现类似的条纹图案。在这种情况下，基于扩散的最简单的模型将产生条纹图案，这需要一种细胞类型应该分泌两种物质，其中一种物质刺激其亲本细胞类型的生长或分化，并且具有低扩散速率或快速失活，另一种物质抑制生长或分化，并且具有较高的扩散速率或不太快速失活。对其中一些结果的初步说明已在别处发表（Swindale 1979）。
The paper describes a model of competition that explains the formation of the ocular dominance stripes found in layer IVc of cat and monkey visual cortex. The main proposal is that synapses exert effects on the growth of other synapses, and that these effects extend over distances of at least 600 μm and vary in magnitude and sign within this distance. Interactions between like type synapses are assumed to be stimulating for distances up to about 200 μm, and inhibitory for distances of 200-600 μm. The reverse is true of interactions between synapses of opposite eye type, where the effects are inhibitory for distances up to about 200 μm and stimulating for longer ones. The interactions are assumed to be circularly symmetric. Growth of, for example, right eye synapses at one point will therefore (a) encourage local growth of right eye synapses and inhibit local growth of left eye synapses and (b) encourage growth of left eye synapses and inhibit growth of right eye synapses in an annular ring surrounding the point of initial increase. At the start of development, right and left eye synapses are assumed to be intermixed randomly within layer IVc. Computer simulations show that a wide variety of conditions incorporating these assumptions will lead to the formation of stripe patterns. These reproduce many of the morphological features of monkey ocular dominance stripes, including Y- and Н-type branches and terminations, the tendency for stripes to run at right angles into the boundaries of the pattern, and to narrow at branch points. The model can explain the effects of monocular deprivation on stripe morphology if it is assumed that the effectiveness of deprived eye synapses in determining rates of growth locally is reduced. The existence of a critical period for these effects can be explained if it is assumed that lateral growth of terminals does not occur, and that some factor such as a limited availability of postsynaptic sites decreases the rate of growth of synapses as their density approaches a maximum. The model can be generalized to account for pattern formation in other systems, such as zebra or mackerel skin, where similar striped patterns occur. In this context, the simplest model based on diffusion that will produce a pattern of stripes requires that one cell type should secrete two substances, one of which stimulates growth or differentiation of its parent cell type and has a low rate of diffusion or is rapidly inactivated, and another that inhibits growth or differentiation and either has a higher rate of diffusion or is less rapidly inactivated. A preliminary account of some of these results has appeared elsewhere (Swindale 1979).