Chevalier G, Deniau J M, Thierry A M, Feger J
Brain Res. 1981 Jun 1;213(2):253-63. doi: 10.1016/0006-8993(81)90232-8.
Controversial data have been reported concerning the effect induced by stimulation of substantia nigra (SN) on the cells of the ipsilateral superior colliculus (SC) in the rat. Stimulation applied within SN activates not only the nigral neurons but also fibers passing through and in the vicinity of SN, especially those of cerebral peduncle (Ped) and optic tract (OT). The effect of SN stimulation has therefore been reinvestigated on two types of preparation: firstly in animals whose Ped--OT fibers were transected rostral to SN; and secondly in rats whose nigral cells destroyed by kainic acid injection. In normal animals, SN stimulation induced both inhibitory and excitatory responses in SC cells. After transection of Ped--OT fibers, SN stimulation no longer induced excitatory but only inhibitory effects. This observation clearly demonstrates that the nigro-tectal pathway is inhibitory. The excitatory responses observed in normal rats are related to activation of Ped--OT fibers at the level of SN. Indeed these excitations induced by SN stimulation still persist in kainic acid lesioned animals. Moreover, stimulation of Ped--OT fibers applied rostral to SN also produce these excitatory effects on SC cells. On the other hand, Ped--OT stimulation not only induces excitations but also inhibitory responses. These latter effects can still be evoked by SN stimulation after kainic acid induced loss of nigral cells. In conclusion the SC receives both excitatory and inhibitory input from Ped--OT fibers and only inhibitory input from nigral cells. This inhibitory nigral control is mainly exerted on cells of intermediate and deep collicular layers.
关于刺激大鼠黑质（SN）对同侧上丘（SC）细胞所产生的影响，已有一些有争议的数据报道。在SN内施加刺激不仅会激活黑质神经元，还会激活穿过SN及其附近的纤维，尤其是大脑脚（Ped）和视束（OT）的纤维。因此，已在两种类型的制备实验中重新研究了SN刺激的效果：第一，在Ped - OT纤维在SN前方被横断的动物中；第二，在通过注射海藻酸破坏黑质细胞的大鼠中。在正常动物中，SN刺激在SC细胞中既诱发抑制性反应，也诱发兴奋性反应。在横断Ped - OT纤维后，SN刺激不再诱发兴奋性反应，而只诱发抑制性效应。这一观察结果清楚地表明黑质 - 顶盖通路是抑制性的。在正常大鼠中观察到的兴奋性反应与SN水平处Ped - OT纤维的激活有关。实际上，由SN刺激诱发的这些兴奋在海藻酸损伤的动物中仍然存在。此外，在SN前方刺激Ped - OT纤维也会对SC细胞产生这些兴奋性效应。另一方面，刺激Ped - OT不仅会诱发兴奋，还会诱发抑制性反应。在海藻酸导致黑质细胞缺失后，SN刺激仍能诱发这些后者的效应。总之，SC接受来自Ped - OT纤维的兴奋性和抑制性输入，以及仅来自黑质细胞的抑制性输入。这种黑质的抑制性控制主要作用于丘中间层和深层的细胞。
