Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada.
Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2023 Sep;209(5):839-854. doi: 10.1007/s00359-023-01663-5. Epub 2023 Aug 5.
Avian flight is guided by optic flow-the movement across the retina of images of surfaces and edges in the environment due to self-motion. In all vertebrates, there is a short pathway for optic flow information to reach pre-motor areas: retinal-recipient regions in the midbrain encode optic flow, which is then sent to the cerebellum. One well-known role for optic flow pathways to the cerebellum is the control of stabilizing eye movements (the optokinetic response). However, the role of this pathway in controlling locomotion is less well understood. Electrophysiological and tract tracing studies are revealing the functional connectivity of a more elaborate circuit through the avian cerebellum, which integrates optic flow with other sensory signals. Here we review the research supporting this framework and identify the cerebellar output centres, the lateral (CbL) and medial (CbM) cerebellar nuclei, as two key nodes with potentially distinct roles in flight control. The CbM receives bilateral optic flow information and projects to sites in the brainstem that suggest a primary role for flight control over time, such as during forward flight. The CbL receives monocular optic flow and other types of visual information. This site provides feedback to sensory areas throughout the brain and has a strong projection the nucleus ruber, which is known to have a dominant role in forelimb muscle control. This arrangement suggests primary roles for the CbL in the control of wing morphing and for rapid maneuvers.
鸟类飞行是由光流引导的，即由于自身运动，导致环境中表面和边缘的图像在视网膜上移动。在所有脊椎动物中，都有一条短的路径来让光流信息到达运动前区域：中脑的视网膜接收区对光流进行编码，然后将其发送到小脑。小脑内光流通路的一个众所周知的作用是控制稳定眼球运动（光运动反应）。然而，该通路在控制运动方面的作用还不太清楚。电生理学和追踪研究揭示了一个更复杂的鸟类小脑回路的功能连接，该回路将光流与其他感觉信号整合在一起。在这里，我们回顾了支持这一框架的研究，并确定了小脑的输出中心，即外侧（CbL）和内侧（CbM）小脑核，作为在飞行控制中具有潜在不同作用的两个关键节点。CbM 接收双侧光流信息，并投射到脑干中的部位，表明其在时间上（例如在向前飞行期间）对飞行控制具有主要作用。CbL 接收单眼光流和其他类型的视觉信息。该部位向大脑中的各个感觉区域提供反馈，并具有强烈的投射到红核，红核已知在控制前肢肌肉方面具有主导作用。这种排列表明 CbL 在控制翅膀变形和快速机动方面具有主要作用。
