Properties of Eye-Head Co-ordination during Visually Guided Gaze Shifts in Humans

当引入间隔任务（注视点FP消失后200毫秒出现目标）时，视导扫视的潜伏期缩短了100毫秒。为什么最短的反应隐藏在日常生活中是本次项目的主题。在第一个实验中，在外周目标出现之前，将FP的颜色从红色变为绿色（RG范式），测量srt，以了解FP偏移在扫视启动中的作用。RG范式将srt与常规任务联系起来。在第二个实验中，眼睛和头部运动系统在注视转移过程中的耦合被检查。当反身性（目标导向）和自愿性（反目标导向）任务交织时，在某些情况下，受试者仅在最初的头部运动中就会出现方向性错误；分流不正确的头部和正确的眼球运动。这一结果与人们普遍持有的观点相反，即在目光转移过程中，头和眼睛之间存在紧密耦合，并表明两者在人类中是独立控制的。两种运动系统之间的耦合比较，以人、猴、猫的顺序比较灵活。最后的实验检验了是否任何向下扫视在低视野范围内都表现出一致的缓慢的开始时间，因为从生态学的角度解释了向下扫视与向上扫视相比的劣势。单纯向下扫视的平均潜伏期明显长于单纯水平扫视的平均潜伏期。斜扫视的水平或向下分量潜伏期与纯水平扫视一样快。结果表明，下视场存在明显的SRT偏置。这些结果揭示了人类目光转移的特性。

Latencies of visually guided saccades (SRTs) are shortened by 100ms when a gap task (target appears 200ms after disappearance of the fixation point FP) is introduced. Why the shortest reaction is hidden in everyday life was the main theme of the present project. In the first experiment, SRTs were measured while a color of the FP was changed from red to green prior to the peripheral target appearance (RG paradigm), to understand the role of the FP offset in saccade initiation. The RG paradigm fastened SRTs relative to the conventional tasks. In the second experiment, coupling between eye and head motor systems during gaze shifts were examined. When the reflexive (target-directed) and voluntary (anti-target-directed) tasks were interleaved, subjects made directional errors in the initial head movements alone in some occasions; diverged incorrect head and correct eye movements. The results are contrast to the commonly held view that there is a tight coupling between head and eye during gaze shifts, and suggest that both are controlled independently in humans. Comparison of the coupling between both motor systems is more flexible in the order of human, monkey and cat. The final experiment examined whether any downward saccades across the lower visual field show uniformly slow onset time, because a disadvantage for downward saccade as compared with upward saccade has been explained from ecological viewpoints. The mean latency of purely downward saccades was significantly longer than that of purely horizontal saccades. However, latency of horizontal or downward components of oblique saccades was as fast as the purely horizontal saccades. The result indicates that there exists an apparent SRT bias within the lower visual field. The properties of human gaze shifts came to light from these results.