PLASTICITY OF OCULAR DOMINANCE COLUMNS IN MONKEY STRIATE CORTEX
PLASTICITY OF OCULAR DOMINANCE COLUMNS IN MONKEY STRIATE CORTEX
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DOI：
10.1098/rstb.1977.0050
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发表时间：
1977-01-01
期刊：
影响因子：
--
通讯作者：
LEVAY, S
中科院分区：
文献类型：
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作者：
HUBEL, DH;WIESEL, TN;LEVAY, S
在幼年猕猴中，一只眼睛在出生后不久就被摘除或缝合闭合，通过各种技术检查了眼优势柱。在两只猴子中，在2周时取出皮质，在1年半时研究皮质。生理记录显示连续的反应，作为一个电极前进沿着层IV C在平行于表面的方向。用Fink-Heimer改良的Nauta方法检查损伤局限于单个外侧膝状体层后的皮质，结果显示，在IV G层中，属于存活眼的柱的宽度显著增加，而属于被切除眼的柱的宽度相应收缩。在一只猴中，在2周龄时进行单眼眼睑闭合，持续18个月，在另一只猴中，在3周龄时进行单眼眼睑闭合，持续7个月，在第三只猴中，在2天时进行单眼眼睑闭合，持续7周。记录从外侧膝状体显示活跃的活动，从剥夺层和通常突然的眼睛过渡层之间的边界。剥夺层中的细胞收缩是中度的-远低于眼睛摘除后的严重程度，同侧比对侧更明显，并且剥夺发作越早越明显。用氚化脯氨酸和氚化岩藻糖的混合物眼内注射后的放射自显影中，末端的标记仅限于与注射眼对应的膝状体层。动物中，开放的眼睛注射显示没有迹象的终端入侵到剥夺层。同样，在顶盖中，没有迹象表明两只眼睛的终端分布有任何变化。除了6个经典的分支外，外侧膝状体的放射自显影还为几个以前未描述的视神经末梢区提供了证据。在皮质四个独立的方法，生理记录，transneuronal放射自显影，Nauta变性，和正常纤维的还原银染色，都同意显示显着收缩的剥夺眼列和扩展的正常眼，与保存正常的重复距离（左眼列加右眼列）。有证据表明，与第3周相比，第2周进行闭合时，柱的变化更严重，闭合同侧的变化更严重。颞叶新月形的代表在第四层C的半球对面的关闭没有表现出明显的不利影响。收缩的第四层柱中的细胞大小和填充密度似乎正常。在一只出生后第二天就注射了一只眼睛的正常猴子中，1周时的皮质放射自显影显示，两只眼睛的输入只有非常轻微的分离;这是平行条带的形式。切线记录在第四层C在8天同样表现出相当大的重叠的投入，虽然一些隔离是明确存在的，在30天的隔离是更先进的。这些初步实验表明，第IV层C柱直到出生后几周才完全发育。两种替代的可能性被认为是占的变化，在层IVG剥夺后的眼优势列。如果我们忽略了新生儿的上述证据，并假设这些眼柱在出生时就已经完全形成，那么在闭上眼睛后，来自正常眼的传入神经必定会扩展它们的领地，可能通过末梢发芽的过程侵入被剥夺的眼柱。另一方面，如果在出生时，每只眼睛的纤维确实占据了所有的IV C层，只有在前6周左右才缩回形成柱状物，也许是通过一个过程。
Ocular dominance columns were examined by a variety of techniques in juvenile macaque monkeys in which one eye had been removed or sutured closed soon after birth. In two monkeys the removal was done at 2 weeks and the cortex studied at 1 1/2 years. Physiological recordings showed continuous responses as an electrode advanced along layer IV C in a direction parallel to the surface. Examination of the cortex with the Fink-Heimer modification of the Nauta method after lesions confined to single lateral-geniculate layers showed a marked increase, in layer IV G, in the widths of columns belonging to the surviving eye, and a corresponding shrinkage of those belonging to the removed eye. Monocular lid closures were made in one monkey at 2 weeks of age, for a period of 18 months, in another at 3 weeks for 7 months, and in a third at 2 days for 7 weeks. Recordings from the lateral geniculate body showed brisk activity from the deprived layers and the usual abrupt eye transitions at the boundaries between layers. Cell shrinkage in the deprived layers was moderate - far less severe than that following eye removal, more marked ipsilaterally than contralaterally, and more marked the earlier the onset of the deprivation. In autoradiographs following eye injection with a mixture of tritiated proline and tritiated fucose the labelling of terminals was confined to geniculate layers corresponding to the injected eye. Animals in which the open eye was injected showed no hint of invasion of terminals into the deprived layers. Similarly in the tectum there was no indication of any change in the distribution of terminals from the two eyes. The autoradiographs of the lateral geniculates provide evidence for several previously undescribed zones of optic nerve terminals, in addition to the six classical subdivisions. In the cortex four independent methods, physiological recording, transneuronal autoradiography, Nauta degeneration, and a reduced-silver stain for normal fibres, all agreed in showing a marked shrinkage of deprived-eye columns and expansion of those of the normal eye, with preservation of the normal repeat distance (left-eye column plus right-eye column). There was a suggestion that changes in the columns were more severe when closure was done at 2 weeks as opposed to 3, and more severe on the side ipsilateral to the closure. The temporal crescent representation in layer IV C of the hemisphere opposite the closure showed no obvious adverse effects. Cell size and packing density in the shrunken IVth layer columns seemed normal. In one normal monkey in which an eye was injected the day after birth, autoradiographs of the cortex at 1 week indicated only a very mild degree of segregation of input from the two eyes; this had the form of parallel bands. Tangential recordings in layer IV C at 8 days likewise showed considerable overlap of inputs, though some segregation was clearly present; at 30 days the segregation was much more advanced. These preliminary experiments thus suggest that the layer IV C columns are not fully developed until some weeks after birth. Two alternate possibilities are considered to account for the changes in the ocular dominance columns in layer IVG following deprivation. If one ignores the above evidence in the newborn and assumes that the columns are fully formed at birth, then after eye closure the afferents from the normal eye must extend their territory, invading the deprived-eye columns perhaps by a process of sprouting of terminals. On the other hand, if at birth the fibres from each eye indeed occupy all of layer IV C, retracting to form the columns only during the first 6 weeks or so, perhaps by a process of …