High-Speed Video-Oculography for Measuring Three-Dimensional Rotation Vectors of Eye Movements in Mice

BackgroundThe mouse is the most commonly used animal model in biomedical research because of recent advances in molecular genetic techniques. Studies related to eye movement in mice are common in fields such as ophthalmology relating to vision, neuro-otology relating to the vestibulo-ocular reflex (VOR), neurology relating to the cerebellum’s role in movement, and psychology relating to attention. Recording eye movements in mice, however, is technically difficult.MethodsWe developed a new algorithm for analyzing the three-dimensional (3D) rotation vector of eye movement in mice using high-speed video-oculography (VOG). The algorithm made it possible to analyze the gain and phase of VOR using the eye’s angular velocity around the axis of eye rotation.ResultsWhen mice were rotated at 0.5 Hz and 2.5 Hz around the earth’s vertical axis with their heads in a 30° nose-down position, the vertical components of their left eye movements were in phase with the horizontal components. The VOR gain was 0.42 at 0.5 Hz and 0.74 at 2.5 Hz, and the phase lead of the eye movement against the turntable was 16.1° at 0.5 Hz and 4.88° at 2.5 Hz.ConclusionsTo the best of our knowledge, this is the first report of this algorithm being used to calculate a 3D rotation vector of eye movement in mice using high-speed VOG. We developed a technique for analyzing the 3D rotation vector of eye movements in mice with a high-speed infrared CCD camera. We concluded that the technique is suitable for analyzing eye movements in mice. We also include a C++ source code that can calculate the 3D rotation vectors of the eye position from two-dimensional coordinates of the pupil and the iris freckle in the image to this article.背景 随着分子遗传学技术的快速发展，小鼠已成为生物医学研究中最常用的实验动物模型。与小鼠眼球运动相关的研究广泛见于多个领域：例如围绕视觉功能的眼科学、研究前庭眼反射（vestibulo-ocular reflex, VOR）的神经耳科学、探究小脑在运动调控中作用的神经科学，以及关注注意力调控的心理学领域。然而，对小鼠的眼球运动进行精准记录在技术上仍存在较大挑战。 方法 本研究开发了一种基于高速视频眼动成像（video-oculography, VOG）分析小鼠眼球运动三维旋转向量的全新算法，该算法可通过眼球绕自身旋转轴的角速度来计算前庭眼反射的增益与相位特征。 结果 实验中将小鼠头部维持在30°俯倾体位，使其绕地球垂直轴以0.5 Hz与2.5 Hz的频率旋转，结果发现其左眼运动的垂直分量与水平分量呈现同相位特征。前庭眼反射的增益在0.5 Hz时为0.42，2.5 Hz时为0.74；眼球运动相对于转台的相位超前在0.5 Hz时为16.1°，2.5 Hz时为4.88°。 结论 据我们所知，本研究首次基于高速视频眼动成像，通过该算法计算了小鼠眼球运动的三维旋转向量。本研究搭建了一套基于高速红外CCD相机的小鼠眼球运动三维旋转向量分析技术，并证实该技术可有效适用于小鼠眼球运动的相关分析。本文附带一段C++源代码，可根据图像中瞳孔与虹膜斑点的二维坐标计算眼球位置的三维旋转向量。