Sahibzada N, Dean P, Redgrave P
J Neurosci. 1986 Mar;6(3):723-33. doi: 10.1523/JNEUROSCI.06-03-00723.1986.
Some studies have reported that stimulation of the superior colliculus in rats produces orienting responses, as it does in a number of species. However, other studies have reported movements resembling avoidance and escape, which are not characteristic of collicular stimulation in other mammals. This apparent discrepancy was investigated by systematically recording the effects on head and body movements of electrical stimulation at a large number of sites throughout the superior colliculus (SC) and surrounding structures. It was found that the nature of the movements observed depended on the location of the stimulating electrode. Contralateral head and body movements resembling orienting and approach were obtained from sites in the intermediate and deep layers in rostral colliculus, the intermediate white layer and immediately surrounding tissue in central colliculus, and in all layers except deep white in caudal colliculus. At the remaining responsive sites, movements resembling avoidance and escape were obtained. The most common response was an ipsilateral cringelike movement of the body that developed into ipsilateral locomotion, followed by running and jumping as the current was increased. These movements were obtained from sites in the superficial and intermediate layers rostrally; from the intermediate gray and the medial superficial and deep layers in central colliculus; and from the deep layers and underlying tegmentum caudally. The distributions of sites, together with evidence from other studies, suggested the following conclusions: Within the superficial layers, avoidance responses were obtained from a region of the superior colliculus that appeared to represent the upper visual field, whereas orienting responses were obtained from a region apparently representing the lower visual field. Stimulation of the area containing the cells of origin of the predorsal bundle produced orientation and approach movements, whereas the avoidance and escape movements were probably mediated by parts of the ipsilateral descending pathway. The stimulation-induced avoidance and escape may reflect the importance of such responses to visual "events," particularly in the upper part of the visual field, in animals, like rats, with many predators.
一些研究报告称，刺激大鼠的上丘会产生定向反应，许多物种都是如此。然而，其他研究报告称出现了类似回避和逃跑的动作，这在其他哺乳动物的丘刺激中并不常见。通过系统记录对整个上丘（SC）和周围结构中大量位点进行电刺激对头部和身体运动的影响，对这一明显差异进行了研究。结果发现，观察到的运动性质取决于刺激电极的位置。在嘴侧丘的中层和深层、中央丘的中间白质层及其紧邻的周围组织，以及尾侧丘除深白质层外的所有层中，可获得类似定向和接近的对侧头部和身体运动。在其余有反应的位点，则获得类似回避和逃跑的动作。最常见的反应是身体同侧的蜷缩样运动，随着电流增加，这种运动发展为同侧移动，随后是奔跑和跳跃。这些运动可从嘴侧的表层和中层位点获得；从中层灰质以及中央丘的内侧表层和深层获得；从尾侧的深层和其下方的被盖获得。这些位点的分布，以及其他研究的证据，提示了以下结论：在表层内，上丘中一个似乎代表上视野的区域产生回避反应，而一个显然代表下视野的区域产生定向反应。刺激包含背侧前束起源细胞的区域会产生定向和接近运动，而回避和逃跑运动可能由同侧下行通路的部分介导。刺激诱导的回避和逃跑可能反映了此类反应对视觉“事件”的重要性，特别是在像大鼠这样有许多捕食者的动物的视野上部。
