A projection by the superior colliculus to the supraoculomotor area (SOA) located dorsal to the oculomotor complex was first described in 1978. This projection’s targets have yet to be identified, although the initial study suggested that vertical gaze motoneuron dendrites might receive this input. Defining the tectal targets is complicated by the fact the SOA contains a number of different cell populations. In the present study, we used anterograde tracers to characterize collicular axonal arbors and retrograde tracers to label prospective SOA target populations in macaque monkeys. Close associations were not found with either superior or medial rectus motoneurons whose axons supply singly innervated muscle fibers. S-group motoneurons, which supply superior rectus multiply innervated muscle fibers, appeared to receive a very minor input, but C-group motoneurons, which supply medial rectus multiply innervated muscle fibers, received no input. A number of labeled boutons were observed in close association with SOA neurons projecting to the spinal cord, or the reticular formation in the pons and medulla. These descending output neurons are presumed to be peptidergic cells within the centrally projecting Edinger–Westphal population. It is possible the collicular input provides a signaling function for neurons in this population that serve roles in either stress responses, or in eating and drinking behavior. Finally, a number of close associations were observed between tectal terminals and levator palpebrae superioris motoneurons, suggesting the possibility that the superior colliculus provides a modest direct input for raising the eyelids during upward saccades.

中文翻译：

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猕猴上眼球运动区目标人群的上丘投射

1978 年首次描述了上丘投射到位于动眼神经复合体背侧的眼球运动上区 (SOA)。该投射的目标尚未确定，尽管初步研究表明垂直注视运动神经元树突可能接收此输入。由于 SOA 包含许多不同的细胞群，因此定义 tectal 目标很复杂。在本研究中，我们使用顺行示踪剂来表征丘轴突乔木和逆行示踪剂来标记猕猴中预期的 SOA 目标种群。未发现与上直肌运动神经元或内直肌运动神经元的密切关联，这些运动神经元的轴突提供单一神经支配的肌纤维。S 组运动神经元，提供上直肌多重神经支配的肌纤维，似乎接收到非常小的输入，但是供应内直肌多重神经支配肌纤维的 C 组运动神经元没有接收到任何输入。观察到许多标记的神经节与投射到脊髓的 SOA 神经元或脑桥和髓质中的网状结构密切相关。这些下行输出神经元被认为是中央投射的 Edinger-Westphal 群体中的肽能细胞。丘脑输入可能为该人群中的神经元提供信号功能，这些神经元在压力反应或饮食行为中发挥作用。最后，在顶盖末梢和上睑提肌运动神经元之间观察到许多密切关联，表明上丘可能为向上扫视期间的眼睑上提提供适度的直接输入。提供内侧直肌多重神经支配的肌纤维，没有收到任何输入。观察到许多标记的神经节与投射到脊髓的 SOA 神经元或脑桥和髓质中的网状结构密切相关。这些下行输出神经元被认为是中央投射的 Edinger-Westphal 群体中的肽能细胞。丘脑输入可能为该人群中的神经元提供信号功能，这些神经元在压力反应或饮食行为中发挥作用。最后，在顶盖末梢和上睑提肌运动神经元之间观察到许多密切关联，表明上丘可能为向上扫视期间的眼睑上提提供适度的直接输入。提供内侧直肌多重神经支配的肌纤维，没有收到任何输入。观察到许多标记的神经节与投射到脊髓的 SOA 神经元或脑桥和髓质中的网状结构密切相关。这些下行输出神经元被认为是中央投射的 Edinger-Westphal 群体中的肽能细胞。丘脑输入可能为该人群中的神经元提供信号功能，这些神经元在压力反应或饮食行为中发挥作用。最后，在顶盖末梢和上睑提肌运动神经元之间观察到许多密切关联，表明上丘可能为向上扫视期间的眼睑上提提供适度的直接输入。