Guido W, Salinger W L, Schroeder C E
Department of Psychology, University of North Carolina-Greensboro 27412.
Exp Brain Res. 1988;70(2):417-28. doi: 10.1007/BF00248366.
Prolonged periods of monocular paralysis alter the physiology of the dorsal lateral geniculate nucleus (LGN), shifting the X/Y cell ratio so that X cells are encountered less frequently than Y cells. The shift in the LGN X/Y cell ratio is observed in both the A-layers of both geniculates whether the innervating eye is paralyzed or mobile. This change in the LGN has been attributed to a mechanism that is sensitive to disruptions in binocular cues. The effects of monocular paralysis in the LGN were used to demonstrate that LGN cells possess a sensitivity to binocular cues of an extraretinal and retinal source. The removal of extraretinal signals, in the form of proprioceptive feedback from the extraocular muscles of the mobile eye, by section of the ophthalmic branch of the Vth cranial nerve, resulted in an immediate and long-lasting reversal in the effects of monocular paralysis. The LGN X/Y ratio was restored to a normal value in the layers innervated by the eye with intact proprioceptive inputs as well as in the layers innervated by the eye in which proprioceptive inputs were removed. In contrast to this, the removal of proprioceptive inputs from the paralyzed eye had no effect on the LGN X/Y ratio. The removal of visual inputs from the mobile eye by section of the optic nerve resulted in an immediate, but somewhat transient reversal in the effects of monocular paralysis. Within the first 25 h after optic nerve section, the LGN X/Y ratio was restored to a normal value in the layers innervated by the eye with intact visual inputs. A transient reversal was also observed when both visual and proprioceptive inputs from the mobile eye were removed. These results are consistent with the belief that the LGN is one site in the visual pathway where proprioceptive and visual signals from the two eyes converge.
长时间的单眼麻痹会改变外侧膝状核（LGN）的生理机能，使X/Y细胞比例发生变化，导致X细胞出现的频率低于Y细胞。无论支配眼是麻痹还是活动的，在两侧膝状体的A层均能观察到LGN中X/Y细胞比例的变化。LGN的这种变化被归因于一种对双眼线索中断敏感的机制。利用单眼麻痹对LGN的影响来证明LGN细胞对来自视网膜外和视网膜来源的双眼线索具有敏感性。通过切断第五脑神经眼支，去除活动眼眼外肌的本体感觉反馈形式的视网膜外信号，导致单眼麻痹的影响立即且持久地逆转。在由具有完整本体感觉输入的眼睛支配的层以及由去除了本体感觉输入的眼睛支配的层中，LGN的X/Y比例恢复到正常值。与此形成对比的是，去除麻痹眼的本体感觉输入对LGN的X/Y比例没有影响。通过切断视神经去除活动眼的视觉输入，导致单眼麻痹的影响立即但有点短暂地逆转。在视神经切断后的最初25小时内，由具有完整视觉输入的眼睛支配的层中LGN的X/Y比例恢复到正常值。当同时去除活动眼的视觉和本体感觉输入时，也观察到短暂的逆转。这些结果与以下观点一致，即LGN是视觉通路中来自两只眼睛的本体感觉和视觉信号汇聚的一个部位。
