ELECTRON-MICROSCOPIC ANALYSIS OF SYNAPTIC INPUT FROM THE PERIGENICULATE NUCLEUS TO THE A-LAMINAE OF THE LATERAL GENICULATE-NUCLEUS IN CATS
ELECTRON-MICROSCOPIC ANALYSIS OF SYNAPTIC INPUT FROM THE PERIGENICULATE NUCLEUS TO THE A-LAMINAE OF THE LATERAL GENICULATE-NUCLEUS IN CATS
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DOI：
10.1002/cne.903100304
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发表时间：
1991-08-15
影响因子：
2.5
通讯作者：
SHERMAN, SM
中科院分区：
文献类型：
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作者：
CUCCHIARO, JB;UHLRICH, DJ;SHERMAN, SM
食肉动物的膝状体周围核被认为是丘脑网状核的一部分，与丘脑的视觉中枢有关。生理学研究表明，主要为GABA能的周膝体神经元对外侧膝体核中的神经元提供反馈抑制。然而，很少有人知道这个反馈途径的解剖组织。为了解决这个问题，我们使用了两种互补的示踪方法来标记周膝状体轴突的电子显微镜研究中的膝状体A-板：辣根过氧化物酶（HRP）的细胞内注射，以填补一个人的周膝状体细胞和轴突;和顺行运输菜豆白细胞凝集素标记的人口周膝状体轴突。标记的周膝状体终端显示功能的F1终端在膝状体神经元：它们是小的，包含黑暗的线粒体，并形成对称的突触接触。我们发现，大多数周膝状体终末（> 90%）在也接受来自视觉皮层的终末的丰富神经支配的区域（例如，“皮质受体”树突）。其余的周膝状体突触（10%）在也接受直接视网膜输入的区域（例如，“视网膜受体”树突）。串行重建的树突突触后到周膝状体终端段表明，这些终端接触两类中继细胞在A-板层（X和Y），虽然我们的初步结论是，一个单独的周膝状体细胞接触只有一类。最后，我们的定量比较标记的周膝状体终端和未标记的F1终端表明，这些周膝状体终端形成一个独特的子集F1终端。我们定量比较了标记的周膝状体终端未标记的F1终端。虽然周膝状体终端的参数完全落在未标记的F1终端的范围内，作为人口，我们发现这两组之间的一致差异。因此，我们的结论是，作为人口，其他来源的F1终端是形态上不同的周膝状体终端和神经支配不同的目标。
The perigeniculate nucleus of carnivores is thought to be a part of the thalamic reticular nucleus related to visual centers of the thalamus. Physiological studies show that perigeniculate neurons, which are primarily GABAergic, provide feedback inhibition onto neurons in the lateral geniculate nucleus. However, little is known about the anatomical organization of this feedback pathway. To address this, we used two complementary tracing methods to label perigeniculate axons for electron microscopic study in the geniculate A-laminae: intracellular injection of horseradish peroxidase (HRP) to fill an individual perigeniculate cell and its axon; and anterograde transport of Phaseolus vulgaris leucoagglutinin to label a population of perigeniculate axons. Labeled perigeniculate terminals display features of F1 terminals in the geniculate neuropil: they are small, contain dark mitochondria, and form symmetric synaptic contacts. We found that most of the perigeniculate terminals (> 90%) contact geniculate cell dendrites in regions that also receive a rich innervation from terminals deriving from visual cortex (e.g., "cortico-recipient" dendrites). The remainder of the perigeniculate synapses (10%) contacted dendrites in regions that also received direct retinal input (e.g., "retino-recipient" dendrites). Serial reconstruction of segments of dendrites postsynaptic to perigeniculate terminals suggests that these terminals contact both classes of relay cell in the A-laminae (X and Y), although our preliminary conclusion is that an individual perigeniculate cell contacts only one class. Finally, our quantitative comparison between labeled perigeniculate terminals and unlabeled Fl terminals indicates that these perigeniculate terminals form a distinct subset of F1 terminals. We quantitatively compared the labeled perigeniculate terminals to unlabeled F1 terminals. Although the parameters of the perigeniculate terminals fell entirely within the range of those for the unlabeled F1 terminals, as populations, we found consistent differences between these two groups. We thus conclude that, as populations, other sources of F1 terminals are morphologically distinct from perigeniculate terminals and innervate different targets.