Functional architecture underlying binocular coordination of eye position and velocity in the larval zebrafish hindbrain
Functional architecture underlying binocular coordination of eye position and velocity in the larval zebrafish hindbrain
复制标题
DOI：
10.1186/s12915-019-0720-y
复制
发表时间：
2019-12-29
期刊：
影响因子：
5.4
通讯作者：
Arrenberg, Aristides B.
中科院分区：
文献类型：
--
作者：
Brysch, Christian;Leyden, Claire;Arrenberg, Aristides B.
研究背景脊椎动物后脑中的眼动积分器（OI）将眼动速度输入转换为持续的位置编码输出，对视网膜图像的稳定性起着至关重要的作用。对于积分器功能和眼睛位置控制的机械理解，需要关于OI和其他眼神经核的调谐的知识。斑马鱼越来越多地用于研究积分功能和感觉运动回路，但精确的神经元调谐到运动变量仍然没有特征。结果在此，我们记录了细胞钙信号，同时唤起单眼和双眼视动性眼运动在不同的慢相眼速度。我们的分析揭示了运动神经元和核间神经元的展神经核以及那些在尾部相邻的后脑卷的眼神经元的解剖分布。每个神经元都被调节到不同程度的眼睛位置和/或速度，并且只有在超过特定的眼睛位置和速度阈值后才被激活。外展神经（5/6节菱形神经）主要编码眼位置，而在7/8节菱形神经中，沿吻尾轴沿着存在速度-位置编码梯度，这可能与储存速度和位置的眼神经结构相对应，并与持续活动产生的前馈机制相一致。位置编码神经元在分布在行为相关动态范围内的眼睛位置阈值处被招募，而速度编码神经元对速度具有更集中的放电阈值。在外展神经中，专门编码一只眼睛的神经元与编码两只眼睛的神经元混合在一起。这些双眼神经元中的许多在共轭眼球运动期间优先活跃，而在单眼眼球运动期间不太活跃。这种差异招聘单眼与共轭任务的功能多样化，在最后的共同运动通路。结论我们定位和功能特点的斑马鱼后脑的眼神经元库。我们的研究结果提供了一个混合的，但特定于任务的双眼代码的证据，并建议产生持久的活动是有组织的沿着在后脑的喙尾轴。
Background The oculomotor integrator (OI) in the vertebrate hindbrain transforms eye velocity input into persistent position coding output, which plays a crucial role in retinal image stability. For a mechanistic understanding of the integrator function and eye position control, knowledge about the tuning of the OI and other oculomotor nuclei is needed. Zebrafish are increasingly used to study integrator function and sensorimotor circuits, yet the precise neuronal tuning to motor variables remains uncharacterized. Results Here, we recorded cellular calcium signals while evoking monocular and binocular optokinetic eye movements at different slow-phase eye velocities. Our analysis reveals the anatomical distributions of motoneurons and internuclear neurons in the nucleus abducens as well as those of oculomotor neurons in caudally adjacent hindbrain volumes. Each neuron is tuned to eye position and/or velocity to variable extents and is only activated after surpassing particular eye position and velocity thresholds. While the abducens (rhombomeres 5/6) mainly codes for eye position, in rhombomeres 7/8, a velocity-to-position coding gradient exists along the rostro-caudal axis, which likely corresponds to the oculomotor structures storing velocity and position, and is in agreement with a feedforward mechanism of persistent activity generation. Position encoding neurons are recruited at eye position thresholds distributed across the behaviourally relevant dynamic range, while velocity-encoding neurons have more centred firing thresholds for velocity. In the abducens, neurons coding exclusively for one eye intermingle with neurons coding for both eyes. Many of these binocular neurons are preferentially active during conjugate eye movements and less active during monocular eye movements. This differential recruitment during monocular versus conjugate tasks represents a functional diversification in the final common motor pathway. Conclusions We localized and functionally characterized the repertoire of oculomotor neurons in the zebrafish hindbrain. Our findings provide evidence for a mixed but task-specific binocular code and suggest that generation of persistent activity is organized along the rostro-caudal axis in the hindbrain.