Enderle J D, Wolfe J W
Department of Electrical and Electronics Engineering, North Dakota State University, Fargo 58105.
Comput Biol Med. 1988;18(3):195-219. doi: 10.1016/0010-4825(88)90046-7.
A frequency response method is used to estimate parameters of a fourth-order model of the oculomotor system and the active state tensions during a saccadic eye movement. The lateral and medial rectus muscle of each eye is modeled as a parallel combination of an active state tension generator with a viscosity and elastic element, connected to a series elastic element. The eyeball is modeled as a sphere connected to a viscosity and elastic element. Each of these elements is assumed to be ideal and linear. The active state tension for each muscle is modeled by a low-pass filtered pulse-step waveform. Initial estimates of the oculomotor mechanical components are based on physiological evidence. Initial estimates of the active state tension are based on an extrapolation of the eye movement trajectory. Horizontal saccadic eye movements were recorded from infrared signals reflected from the anterior surface of the cornea and then digitized. Parameter estimates were calculated for the model by using a conjugate gradient search program which minimizes the integral of the absolute value of the squared error between the model and the data. The predictions of the model are shown to be in good agreement with the data. Final estimates of motoneuronal activity demonstrate that the agonist muscle is maximally stimulated during the early portion of a saccadic eye movement regardless of the amplitude of the saccade; only the duration of the maximal stimulation affects the size of the saccade. The antagonist muscle is completely inhibited during the period of maximum agonist muscle stimulation. Furthermore, it is demonstrated that saccade motoneuronal activity is a stochastic phenomenon.
一种频率响应方法被用于估计眼球运动系统四阶模型的参数以及扫视眼动期间的主动状态张力。每只眼睛的外直肌和内直肌被建模为一个主动状态张力发生器与一个粘性和弹性元件的并联组合，该组合连接到一个串联弹性元件。眼球被建模为一个连接到粘性和弹性元件的球体。假设这些元件中的每一个都是理想且线性的。每块肌肉的主动状态张力由一个低通滤波后的脉冲 - 阶跃波形建模。眼球运动机械组件的初始估计基于生理学证据。主动状态张力的初始估计基于眼动轨迹的外推。水平扫视眼动通过从角膜前表面反射的红外信号进行记录，然后数字化。通过使用共轭梯度搜索程序为模型计算参数估计值，该程序使模型与数据之间平方误差绝对值的积分最小化。模型的预测结果与数据显示出良好的一致性。运动神经元活动的最终估计表明，无论扫视幅度如何，在扫视眼动的早期部分，主动肌都会受到最大程度的刺激；只有最大刺激的持续时间会影响扫视的大小。在主动肌最大刺激期间，拮抗肌会被完全抑制。此外，还证明了扫视运动神经元活动是一种随机现象。
