Redgrave P, Marrow L, Dean P
Department of Psychology, University of Sheffield, U.K.
Neuroscience. 1992 Oct;50(3):571-95. doi: 10.1016/0306-4522(92)90448-b.
Recent evidence suggests that projections from the superior colliculus to the brainstem in rat are organized into a series of anatomically segregated output channels. To understand how collicular function may be modified by the basal ganglia it is important to know whether particular output modules of the superior colliculus can be selectively influenced by input from substantia nigra. The purpose of the present study was, therefore, to examine in more detail topography within the nigrotectal system in the rat. Small injections (10-50 nl) of a 1% solution of wheatgerm agglutinin conjugated with horseradish peroxidase were made at different locations within substantia nigra and surrounding structures. A discontinuous puff-like pattern of anterogradely transported label was found in medial and caudal parts of the ipsilateral intermediate layers of the superior colliculus. In contrast, the rostrolateral enlargement of the intermediate layers contained a greater density of more evenly distributed terminal label. Injection sites associated with this dense pattern of laterally located label were concentrated in lateral pars reticulata, while the puff-like pattern was produced by injections into ventromedial pars reticulata. Retrograde tracing experiments with the fluorescent dyes True Blue and Fast Blue revealed that injections involving the rostrolateral intermediate layers were consistently associated with a restricted column of labelled cells in the dorsolateral part of ipsilateral pars reticulata. Comparable injections into medial and caudal regions of the superior colliculus produced retrograde labelling in ventral and medial parts of the rostral two-thirds of pars reticulata. Both anterograde and retrograde tracing data indicated that contralateral nigrotectal projections arise from cells located in ventral and medial pars reticulata. The present results suggest that the main ipsilateral projection from substantia nigra pars reticulata to the superior colliculus comprises two main components characterized by regionally segregated populations of output cells and spatially separated zones of termination. Of particular interest is the apparent close alignment between terminal zones of the nigrotectal channels and previously defined populations of crossed descending output cells in the superior colliculus. Thus, the rostrolateral intermediate layers contain a concentration of terminals specifically from dorsolateral pars reticulata and output cells which project to the contralateral caudal medulla and spinal cord. Conversely, the medial and caudal intermediate layers receive terminals from ventral and medial pars reticulata and contain cells which project specifically to contralateral regions of the paramedian pontine and medullary reticular formation.(ABSTRACT TRUNCATED AT 400 WORDS)
最近的证据表明，大鼠中从视上丘到脑干的投射被组织成一系列解剖学上分离的输出通道。为了了解基底神经节如何改变视丘的功能，重要的是要知道视上丘的特定输出模块是否能被黑质的输入选择性地影响。因此，本研究的目的是更详细地研究大鼠黑质 - 视丘系统内的拓扑结构。在黑质及其周围结构的不同位置注射1%与辣根过氧化物酶结合的麦胚凝集素溶液（10 - 50 nl）。在同侧视上丘中间层的内侧和尾部发现了一种不连续的、类似 puff 状的顺行运输标记模式。相比之下，中间层的 rostrolateral 扩大区域含有密度更高、分布更均匀的终末标记。与这种位于外侧的密集标记模式相关的注射部位集中在外侧网状部，而 puff 状模式是由注入腹内侧网状部产生的。用荧光染料真蓝和快蓝进行的逆行追踪实验表明，涉及 rostrolateral 中间层的注射始终与同侧网状部背外侧部分的一列受限标记细胞相关。对视上丘内侧和尾部区域进行类似的注射，在网状部前三分之二的腹侧和内侧部分产生逆行标记。顺行和逆行追踪数据均表明，对侧黑质 - 视丘投射起源于位于腹侧和内侧网状部的细胞。目前的结果表明，从黑质网状部到视上丘的主要同侧投射包括两个主要成分，其特征是输出细胞的区域分离群体和空间上分开的终末区域。特别有趣的是，黑质 - 视丘通道的终末区域与视上丘中先前定义的交叉下行输出细胞群体之间明显紧密对齐。因此，rostrolateral 中间层含有专门来自背外侧网状部的终末集中区以及投射到对侧尾侧延髓和脊髓的输出细胞。相反，内侧和尾部中间层接受来自腹侧和内侧网状部的终末，并含有专门投射到对侧脑桥旁正中核和延髓网状结构区域的细胞。（摘要截断于400字）
