Lapsansky Anthony B, Kreyenmeier Philipp, Spering Miriam, Wylie Douglas R, Altshuler Douglas L
Salish Sea Research Center, Northwest Indian College, Bellingham, WA 98226, USA.
Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
Proc Biol Sci. 2025 Jan;292(2038):20242015. doi: 10.1098/rspb.2024.2015. Epub 2025 Jan 15.
To maintain stable vision, behaving animals make compensatory eye movements in response to image slip, a reflex known as the optokinetic response (OKR). Although OKR has been studied in several avian species, eye movements during flight are expected to be minimal. This is because vertebrates with laterally placed eyes typically show weak OKR to nasal-to-temporal motion (NT), which simulates typical forward locomotion, compared with temporal-to-nasal motion (TN), which simulates atypical backward locomotion. This OKR asymmetry is also reflected in the pretectum, wherein neurons sensitive to global visual motion also exhibit a TN bias. Hummingbirds, however, stabilize visual motion in all directions through whole-body movements and are unique among vertebrates in that they lack a pretectal bias. We therefore predicted that OKR in hummingbirds would be symmetrical. We measured OKR in restrained hummingbirds by presenting gratings drifting across a range of speeds. OKR in hummingbirds was asymmetrical, although the direction of asymmetry varied with stimulus speed. Hummingbirds moved their eyes largely independently of one another. Consistent with weak eye-to-eye coupling, hummingbirds also exhibited disjunctive OKR to visual motion simulating forward and backward translation. This unexpected oculomotor behaviour, previously unexplored in birds, suggests a potential role for compensatory eye movements during flight.
为了保持稳定的视觉，活动中的动物会对图像滑动做出补偿性眼动，这种反射被称为视动反应（OKR）。尽管已经在几种鸟类中研究了OKR，但预计飞行过程中的眼动会很少。这是因为眼睛横向排列的脊椎动物，与模拟非典型向后运动的颞侧到鼻侧运动（TN）相比，通常对模拟典型向前运动的鼻侧到颞侧运动（NT）表现出较弱的OKR。这种OKR不对称性也反映在顶盖前区，其中对整体视觉运动敏感的神经元也表现出TN偏好。然而，蜂鸟通过全身运动在各个方向上稳定视觉运动，并且在脊椎动物中独一无二的是它们没有顶盖前区偏好。因此，我们预测蜂鸟的OKR将是对称的。我们通过呈现以一系列速度漂移的光栅来测量受限蜂鸟的OKR。蜂鸟的OKR是不对称的，尽管不对称的方向随刺激速度而变化。蜂鸟的眼睛在很大程度上彼此独立移动。与较弱的眼间耦合一致，蜂鸟对模拟向前和向后平移的视觉运动也表现出分离的OKR。这种以前在鸟类中未被探索过的意外眼动行为，表明了飞行过程中补偿性眼动的潜在作用。
