van den Berg A V
Department of Physiology I, Faculty of Medicine, Erasmus University, Rotterdam, The Netherlands.
Exp Brain Res. 1988;72(1):95-108. doi: 10.1007/BF00248504.
The predictive component of human smooth pursuit was studied by perturbing sinusoidal target motion at unpredictable instants. The disturbances consisted of either a brief period of stabilization of the target on the fovea or a replacement of the sine by a ramp displacement for half a period. To minimize the effects of a possible change of the tracking strategy by the subject the transitions were masked and only the initial part of the response to the disturbance was analyzed. After stabilization on the fovea the eye oscillation continued at the frequency of the preceding target movement for about one half-cycle, whereupon the oscillation was rapidly damped. The mean unidirectional smooth eye acceleration was 70% of the mean unidirectional target acceleration prior to the stabilization. This suggests that during pursuit of a sinusoidal target movement about 75% of the oculomotor response is generated by predictive processes. When the sine was replaced by a ramp, starting at the velocity zero-crossing, the eye accelerated away from the target for ca. 180 ms irrespective of the frequency of prior tracking. In contrast, when the ramp started at the peak velocity of the sinusoidal target motion the eye accelerated away from the target for more than a quarter period. After foveal stabilization during pursuit of a pseudorandom stimulus, the eye continued to oscillate for less than one period at approximately the highest frequency present in the stimulus. The frequency characteristics of human smooth pursuit of predictable as well as unpredictable target motion were correctly simulated by a model, which derived its predictive properties from a lead element, tuned to the current frequency of the target motion.
通过在不可预测的时刻干扰正弦目标运动，对人类平滑追踪的预测成分进行了研究。干扰包括目标在中央凹短暂稳定一段时间，或者在半个周期内用斜坡位移取代正弦。为了尽量减少受试者可能改变追踪策略的影响，对转换过程进行了掩盖，并且只分析对干扰的反应的初始部分。在目标稳定在中央凹之后，眼球振荡以先前目标运动的频率持续大约半个周期，随后振荡迅速衰减。在稳定之前，单向眼球平均平滑加速度是单向目标平均加速度的70%。这表明在追踪正弦目标运动期间，约75%的动眼反应是由预测过程产生的。当从速度过零点开始用斜坡取代正弦时，无论先前追踪的频率如何，眼球都会背离目标加速约180毫秒。相反，当斜坡从正弦目标运动的峰值速度开始时，眼球背离目标加速超过四分之一个周期。在追踪伪随机刺激过程中，中央凹稳定后，眼球以刺激中出现的大约最高频率继续振荡不到一个周期。一个模型正确地模拟了人类对可预测和不可预测目标运动的平滑追踪的频率特性，该模型从一个根据目标运动的当前频率进行调整的超前元件获得其预测特性。
