Dean P, Redgrave P, Sahibzada N, Tsuji K
Neuroscience. 1986 Oct;19(2):367-80. doi: 10.1016/0306-4522(86)90267-8.
Stimulation of the superior colliculus in rats produces movements of the head and body that resemble either orientation and approach towards a contralateral stimulus, or avoidance of, or escape from, such a stimulus. A variety of evidence indicates that the crossed descending pathway, which runs in the contralateral predorsal bundle to the pontomedullary reticular formation and the spinal cord, is involved in orienting movements. The nature of this involvement was investigated, by assessing the effects on tectally-elicited movements of midbrain knife-cuts intended to section the pathway as it crosses midline in the dorsal tegmental decussation. As expected, ipsilateral movements resembling avoidance or escape were little affected by dorsal tegmental decussation section, whereas contralateral circling movements of the body were almost abolished. However, contralateral movements of the head in response to electrical stimulation were not eliminated, nor were orienting head movements to visual or tactile stimuli. There was some suggestion that section of the dorsal tegmental decussation increased the latency of head movements from electrical stimulation at lateral sites, and decreased the accuracy of orienting movements to sensory stimuli. These results support the view that the crossed tectoreticulospinal system is concerned with approach rather than avoidance movements. However, it appears that other, as yet unidentified, tectal efferent systems are also involved in orienting head movements. It is possible that this division of labour may reflect functional differences between various kinds of apparently similar orienting responses. One suggestion is that the tectoreticulospinal system is concerned less in open-loop orienting responses (that are initiated but not subsequently guided by sensory stimuli), than in following or pursuit movements.
刺激大鼠上丘会引发头部和身体的运动，这些运动类似于对侧刺激的定向和趋近，或者对这种刺激的回避或逃离。各种证据表明，交叉下行通路，即通过对侧背侧前束延伸至脑桥延髓网状结构和脊髓的通路，参与了定向运动。通过评估旨在切断该通路在背侧被盖交叉处交叉中线时对顶盖诱发运动的影响，对这种参与的性质进行了研究。正如预期的那样，类似回避或逃离的同侧运动几乎不受背侧被盖交叉切断的影响，而身体的对侧转圈运动几乎被消除。然而，对电刺激的对侧头部运动并未消除，对视觉或触觉刺激的定向头部运动也未消除。有迹象表明，背侧被盖交叉切断会增加外侧部位电刺激引起的头部运动潜伏期，并降低对感觉刺激的定向运动准确性。这些结果支持这样一种观点，即交叉的顶盖网状脊髓系统与趋近运动而非回避运动有关。然而，似乎其他尚未确定的顶盖传出系统也参与了定向头部运动。这种分工可能反映了各种看似相似的定向反应之间的功能差异。一种观点认为，顶盖网状脊髓系统在开环定向反应（由感觉刺激启动但随后不受其引导）中的参与程度低于在跟随或追踪运动中的参与程度。
