Department of Neurology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Neuroscience Center Zurich (ZNZ), University of Zurich and ETH Zurich, Zurich, Switzerland.
J Neurosci Res. 2023 Sep;101(9):1504-1518. doi: 10.1002/jnr.25220. Epub 2023 Jun 14.
To optimize performance during vital tasks, animals are capable of tuning rhythmic neural signals that drive repetitive behaviors, such as motor reflexes under constant sensory stimuli. In the oculomotor system, animals track the moving image during slow phases while repetitively resetting the eye position from the eccentricity during quick phases. During optokinetic response (OKR), larval zebrafish occasionally show a delayed quick phase; thus, the eyes remain tonically deviated from the center. In this study, we scrutinized OKR in larval zebrafish under a broad range of stimulus velocities to determine the parametric property of the quick-phase delay. A prolonged stimulation revealed that the slow-phase (SP) duration-the interval between two quick phases-was tuned increasingly over time toward a homeostatic range, regardless of stimulus velocity. Attributed to this rhythm control, larval zebrafish exhibited a tonic eye deviation following slow phases, which was especially pronounced when tracking a fast stimulus over an extended time period. In addition to the SP duration, the fixation duration between spontaneous saccades in darkness also revealed a similar adaptive property after the prolonged optokinetic stimulation. Our results provide a quantitative description of the adaptation of rhythmic eye movements in developing animals and pave the way for potential animal models for eye movement disorders.
为了在关键任务中优化性能，动物能够调整驱动重复行为的节奏神经信号，例如在恒定的感觉刺激下的运动反射。在眼球运动系统中，动物在缓慢相期间跟踪移动的图像，同时在快速相期间从偏心率重复重置眼睛位置。在视动反应（OKR）中，幼鱼偶尔会表现出延迟的快速相；因此，眼睛会持续从中心偏离。在这项研究中，我们在广泛的刺激速度下仔细研究了幼鱼的 OKR，以确定快速相延迟的参数特性。长时间的刺激表明，即使在不同的刺激速度下，慢相（SP）持续时间——两个快速相之间的间隔——也会随着时间的推移逐渐调整到一个稳定范围。由于这种节律控制，幼鱼在慢相后会表现出持续的眼睛偏差，尤其是在长时间跟踪快速刺激时。除了 SP 持续时间外，在黑暗中自发扫视之间的注视持续时间在长时间的视动刺激后也表现出类似的适应性特征。我们的研究结果提供了对发育中动物节律性眼球运动适应的定量描述，并为眼球运动障碍的潜在动物模型铺平了道路。
