Target selection by surgically misdirected optic fibers in the tectum of goldfish
Target selection by surgically misdirected optic fibers in the tectum of goldfish
复制标题
金鱼顶盖中手术误导光纤的目标选择
DOI：
10.1523/jneurosci.04-01-00234.1984
复制
发表时间：
1984
影响因子：
5.1
通讯作者：
R. Meyer
中科院分区：
文献类型：
--
作者：
R. Meyer
这项研究测试了再生光纤读取顶盖标记的能力，从而在消除初始位置、视神经通路和纤维间相互作用作为有用线索时，生长到适当的顶盖位点。还检查了这些标记物在顶盖长期去视神经支配下的稳定性。在成年金鱼中，将支配后视顶盖的光纤从顶盖中分离出来，并插入相对“宿主”顶盖的内侧前部区域。通常，该位置的纤维要么支配内侧前顶盖，要么沿着视神经通路的内侧部分进入中后顶盖。通过在偏转时或在偏转前长达18个月的不同时间摘除其对侧眼睛，使宿主顶盖失去所有其他光纤的神经支配。 1至11个月后，通过放射自显影和电生理学检查这些偏转纤维再生为宿主顶盖的情况。在插入部位，偏转的纤维分裂成大小大致相等的两组。一组直接进入内侧顶盖的视神经层，并从后外侧穿过顶盖的内侧半部进入外侧半部。第二组沿着几乎直接的路径到达外侧顶盖，有时穿过顶盖的深层细胞层，其中通常找不到光纤。这些纤维随后进入顶盖外侧边缘的视神经层并向后生长。在来自中后顶盖的光纤类似地偏转的对照中没有看到第二条路径。相反，生长几乎完全向后定向。平均 1.5 个月，偏转的后侧纤维优先分布在顶盖的外侧半部。光密度测量表明，与内侧后标记相比，后后标记有近 4 倍的差异。相比之下，内侧后纤维偏转的对照组的内侧颗粒数是外侧颗粒数的 4 倍。也有后向优于前向的偏好，但这很弱。没有证据表明偏转前长时间的视神经去神经支配或后后纤维偏转后长时间的视神经去神经支配会减少外侧优于内侧的偏好。这些发现支持这样的观点，即存在稳定的顶盖标记，内侧和外侧光纤有差异地读取这些标记。然而，在任何情况下，偏转纤维的神经支配都不像正常投射那样具有选择性。（摘要截断为 400 字）
This study tested the capacity of regenerating optic fibers to read tectal markers and thereby grow to their appropriate tectal loci when initial position, optic pathway, and interfiber interactions are eliminated as useful cues. The stability of these markers with long- term optic denervation of the tectum was also examined. In adult goldfish optic fibers innervating lateroposterior optic tectum were dissected free of tectum and inserted into the medial anterior region of the opposite “host” tectum. Normally, fibers at this position either innervate medial anterior tectum or follow the medial division of the optic pathway into medioposterior tectum. Host tectum was denervated of all other optic fibers by enucleating its contralateral eye either at the time of the deflection or at various times up to 18 months prior to deflection. The regeneration of these deflected fibers into host tectum was examined by autoradiography and electrophysiology at 1 to 11 months later. At the insertion site deflected fibers split into two groups of roughly equal size. One group directly entered the optic layers of medial tectum and grew posterolaterally across the medial half of tectum into the lateral half. The second group followed an almost direct path to the lateral tectum, sometimes traversing through the deep cell layers of tectum in which optic fibers are not usually found. These fibers subsequently entered the optic layers at the lateral edge of tectum and grew posteriorly. This second path was not seen in controls in which optic fibers from medioposterior tectum were similarly deflected. Instead growth was almost entirely posteriorly directed. On the average by 1.5 months deflected lateroposterior fibers were preferentially distributed in the lateral half of the tectum. Densitometric measurements indicated nearly a 4-fold difference in lateroposterior compared with medial posterior labeling. By contrast, controls in which medial posterior fibers were deflected had 4 times more grains medially than laterally. There was also a posterior over anterior preference, but this was weak. There was no suggestion that long periods of optic denervation prior to deflection or long postoperative periods after deflection of lateroposterior fibers diminished the lateral over medial preference. These findings support the idea that stable tectal markers exist which are differentially read by medial and lateral optic fibers. However, in no case was the innervation by deflected fibers as selective as in the normal projection.(ABSTRACT TRUNCATED AT 400 WORDS)