Changes in synaptic density after developmental compression or expansion of retinal input to the superior colliculus.
Changes in synaptic density after developmental compression or expansion of retinal input to the superior colliculus.
复制标题
发育压缩或视网膜输入扩张至上丘后突触密度的变化。
DOI：
10.1002/cne.903300402
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Finlay,BL
中科院分区：
文献类型：
--
作者：
Xiong,M;Finlay,BL
通过将“压缩”的视网膜投影引入低于正常的顶盖体积，可以使上丘的视网膜投影变得异常密集，或者通过发育早期的单眼摘除来异常地保留。细胞数量、轴突乔木、树突乔木和突触密度的任何或所有特征都可以潜在地进行调整，以补偿一个细胞群与另一个细胞群会聚的这种变化。我们检查了新生儿部分顶盖消融或单眼剜除对仓鼠上丘浅灰层突触长度、密度和突触类别相对数量的影响。单眼剜除导致与剩余眼睛同侧的丘浅灰层突触密度减少。这种密度的降低完全是由于具有圆形囊泡、大的不对称末端特化和视网膜丘状末端的苍白线粒体特征（RLP突触）的突触数量减少所致。任何其他突触类别都没有代偿性增加。单眼细胞核中的 RLP 突触较大。部分顶盖消融对突触密度没有影响，对不同突触类型的相对比例也没有影响。 RLP 类的突触略小于正常突触。这些结果表明，突触密度通常处于最大值，不能通过潜在输入的增加而改变。然而，可以通过减少输入数量来降低密度。末端类别似乎在丘体积内不会相互竞争，这表明突触后细胞控制其潜在输入的类别和数量。
The retinal projection to the superior colliculus can be made abnormally dense by inducing a “compressed” retinal projection into a subnormal tectal volume, or abnormally spares by monocular enucleation early in development. Any or all of the features of cell number, axonal arbor, dendritic arbor, and synaptic density could potentially be adjusted to compensate for such variations in the convergence of one cell population on another. We have examined the consequences of neonatal partial tectal ablation or monocular enucleation for synaptic length, density, and relative numbers of synapse classes in the superficial gray layer of the hamster superior colliculus.Monocular enucleation resulted in a reduction of synaptic density in the superficial gray layer of the colliculus ipsilateral to the remaining eye. This decrease in density was entirely accounted for by a reduction of the number of synapses with round vesicles, large asymmetric terminal specializations, and pale mitochondria characteristic of retinocollicular terminals (RLP synapses). There was no compensatory increase in any other synaptic class. RLP synapses were larger in monocular enucleates.Partial tectal ablation had no effect on synaptic density, nor on the relative proportions of different synaptic types. Synapses of the RLP class were slightly smaller than normal. These results suggest that synaptic density is normally at a maximum that cannot be altered by increases in potential input. However, density may be reduced by decreasing the number of inputs. Terminal classes do not appear to compete with each other within the collicular volume, suggesting that postsynaptic cells control both the classes and numbers of their potential inputs.