Pakan Janelle M P, Wylie Douglas R W
Division of Neuroscience, University of Alberta, Edmonton, Alberta, Canada T6G 2E9.
J Comp Neurol. 2006 Dec 10;499(5):732-44. doi: 10.1002/cne.21108.
Neurons in the pretectal nucleus lentiformis mesencephali (LM) are involved in the analysis of optic flow. LM provides mossy fiber inputs to folia VI-VIII of the posterior cerebellum and IXcd of the vestibulocerebellum. Previous research has shown that the vestibulocerebellum is involved in visual-vestibular integration supporting gaze stabilization. The function of folia VI-VIII in pigeons is not well understood; however, these folia receive input from a tectopontine system, which is likely involved with analyzing local motion as opposed to optic flow. We sought to determine whether the mossy fiber input from LM to IXcd differs from that to VI-VIII. Fluorescent retrograde tracers were injected into these folia, and the pattern of labeling in LM was observed. Large multipolar neurons were labeled throughout the rostrocaudal extent of LM. There was a clear mediolateral difference: 74.3% of LM neurons projecting to IXcd were located in the lateral subnucleus of LM (LMl), whereas 73.8% of LM neurons projecting to VI-VIII were found in medial LM (LMm). This suggests that the subnuclei of LM have differing roles. In particular, the LMl-IXcd pathway is involved in generating the optokinetic response. We suggest that the pathway from LMm to VI-VIII is integrating optic flow and local motion to support various oculomotor and visuomotor behaviors, including obstacle avoidance during locomotion.
中脑豆状核前核（LM）中的神经元参与视流分析。LM向后小脑的小叶VI - VIII和前庭小脑的IXcd提供苔藓纤维输入。先前的研究表明，前庭小脑参与支持注视稳定的视觉 - 前庭整合。鸽子中小叶VI - VIII的功能尚不清楚；然而，这些小叶接受来自顶盖脑桥系统的输入，该系统可能与分析局部运动而非视流有关。我们试图确定从LM到IXcd的苔藓纤维输入是否与到VI - VIII的不同。将荧光逆行示踪剂注入这些小叶，并观察LM中的标记模式。在LM的整个 rostrocaudal范围内标记了大型多极神经元。存在明显的内外侧差异：投射到IXcd的LM神经元中有74.3%位于LM的外侧亚核（LMl），而投射到VI - VIII的LM神经元中有73.8%位于LM内侧（LMm）。这表明LM的亚核具有不同的作用。特别是，LMl - IXcd通路参与产生视动反应。我们认为从LMm到VI - VIII的通路正在整合视流和局部运动，以支持各种眼球运动和视觉运动行为，包括运动过程中的避障。
