Strategy of eye-head coordination for better dynamic visual acuity

为了研究头部旋转时眼-头协调对动态视力（DVA）的贡献，我进行了以下两个实验。实验一：要求正常受试者（n=84）按随机顺序阅读并回答3个数字。在自愿向右旋转期间，CRT显示器上的数字以90度/秒的速度向右移动。进行了30次试验，正确回答的次数（满分；3 × 30 = 90）作为DVA评分。DVA评分的平均值为37.0，标准差为7.8。实验二：6名正常受试者重复上述实验两周。3名受试者每天进行125次试验（HT组），另外3名受试者每天进行25次试验（LT组）。HT组DVA评分由39.7提高至50.3。同样，LT组由41.3增加到52.3。然而，DVA训练后自发性头部运动的变化完全取决于受试者组。虽然LT组水头峰值流速从62.1 ~ 30.1℃/s下降，但HT组水头峰值流速明显提高了43.3 ~ 79.0℃/s。LT组的策略似乎是合理的，因为在这种头部状态下，左眼运动被认为是由VOR引起的，这干扰了对移动目标的跟踪。HT集团的战略是怎样的？HT组受试者OZ的数据给了我很大的提示。他的头部旋转可以较早开始，因此在出现运动目标时处于减速阶段。因此，我认为向左加速引起的右眼运动为VOR。我把这个想法命名为“反转VOR假说”。根据这一假设，向右VOR和向右追击形成了高速的向右凝视速度。事实上，实验对象OZ表现出80度/秒的向右凝视速度，这不能仅仅用追逐眼运动来解释。这种“反向VOR假说”为更好的DVA提供了有效的训练途径。

To investigate the contribution of eye-head coordination for dynamic visual acuity (DVA) during head rotation, I performed following two experiments.Experiment I : Normal subjects (n=84) were asked to read and answer 3 numerals, presented sequentially at random order. The numerals moved rightward at 90 deg/s on a CRT monitor during voluntary rightward rotation. Thirty trials were carried out and numbers of correct answers (full score ; 3 x 30 = 90) were evaluated as DVA score. Mean and SD of their DVA score was 37.0 and 7.8.Experiment II : Six normal subjects repeated the same trial as above for two weeks. Three subjects conducted 125 trials a day (HT group) and another three ones did 25 trials a day (LT group). DVA score in HT group increased from 39.7 to 50.3. Similarly, that in LT group increased from 41.3 to 52.3. The changes of voluntary head motion followed by DVA training, however, completely depended on the subject group. Although the peak head velocity in LT group decreased from 62.1 to 30.1 deg/s, that in HT group apparently increased 43.3 to 79.0 deg/s. The strategy of LT group seems to be reasonable because in this head condition leftward eye movements are thought to be evoked by VOR, which disturbs tracking a moving target. How is the strategy of HT group? Data of subject OZ in HT group gave me a big hint. His head rotation could make an early start and was consequently in deceleration stage when a moving target appeared. Therefore, I considered that leftward acceleration evoked rightward eye movements as VOR. I named this idea "reversal VOR hypothesis". According this hypothesis, rightward VOR and rightward pursuit made a high-speed rightward gaze velocity. Indeed, subject OZ showed 80 deg/s rightward gaze velocity, which can not be explained by only pursuit eye movements.This "reversal VOR hypothesis" holds the possibility of making effective training way for better DVA.