Centre for Vision Research, York University, Toronto, Ontario, Canada.
Vision: Science to Applications (VISTA), York University, Toronto, Ontario, Canada.
J Neurophysiol. 2019 Nov 1;122(5):1946-1961. doi: 10.1152/jn.00072.2019. Epub 2019 Sep 18.
Nonhuman primates have been used extensively to study eye-head coordination and eye-hand coordination, but the combination-eye-head-hand coordination-has not been studied. Our goal was to determine whether reaching influences eye-head coordination (and vice versa) in rhesus macaques. Eye, head, and hand motion were recorded in two animals with search coil and touch screen technology, respectively. Animals were seated in a customized "chair" that allowed unencumbered head motion and reaching in depth. In the reach condition, animals were trained to touch a central LED at waist level while maintaining central gaze and were then rewarded if they touched a target appearing at 1 of 15 locations in a 40° × 20° (visual angle) array. In other variants, initial hand or gaze position was varied in the horizontal plane. In similar control tasks, animals were rewarded for gaze accuracy in the absence of reach. In the Reach task, animals made eye-head gaze shifts toward the target followed by reaches that were accompanied by prolonged head motion toward the target. This resulted in significantly higher head velocities and amplitudes (and lower eye-in-head ranges) compared with the gaze control condition. Gaze shifts had shorter latencies and higher velocities and were more precise, despite the lack of gaze reward. Initial hand position did not influence gaze, but initial gaze position influenced reach latency. These results suggest that eye-head coordination is optimized for visually guided reach, first by quickly and accurately placing gaze at the target to guide reach transport and then by centering the eyes in the head, likely to improve depth vision as the hand approaches the target. Eye-head and eye-hand coordination have been studied in nonhuman primates but not the combination of all three effectors. Here we examined the timing and kinematics of eye-head-hand coordination in rhesus macaques during a simple reach-to-touch task. Our most novel finding was that (compared with hand-restrained gaze shifts) reaching produced prolonged, increased head rotation toward the target, tending to center the binocular field of view on the target/hand.
非人类灵长类动物被广泛用于研究眼-头协调和眼-手协调，但眼-头-手协调组合尚未被研究。我们的目标是确定在恒河猴中，伸手是否会影响眼-头协调（反之亦然）。使用搜索线圈和触摸屏技术分别记录两只动物的眼睛、头部和手部运动。动物坐在一个定制的“椅子”上，该椅子允许头部不受阻碍地运动和深入伸手。在伸手条件下，动物被训练在保持中央凝视的同时触摸中央 LED，然后如果它们触摸出现在 40°×20°（视场）阵列中 15 个位置之一的目标，就会得到奖励。在其他变体中，初始手或注视位置在水平平面上变化。在类似的控制任务中，动物在没有伸手的情况下因注视准确性而获得奖励。在伸手任务中，动物会先进行眼-头注视转移以朝向目标，然后进行伴随头部长时间朝向目标的伸手。这导致头部速度和幅度显著增加（眼-头范围降低），与注视控制条件相比。注视转移的潜伏期更短，速度更快，更精确，尽管没有注视奖励。初始手位置不会影响注视，但初始注视位置会影响伸手潜伏期。这些结果表明，眼-头协调是为视觉引导的伸手而优化的，首先快速准确地将注视放置在目标上以引导伸手运输，然后将眼睛居中在头部，可能是为了在手部接近目标时改善深度视觉。非人类灵长类动物的眼-头和眼-手协调已经被研究过，但没有研究过所有三个效应器的组合。在这里，我们在恒河猴进行简单的伸手触摸任务时检查了眼-头-手协调的时间和运动学。我们最新颖的发现是（与手部限制的注视转移相比）伸手会产生长时间、增加的头部向目标的旋转，使双眼视场的中心对准目标/手。
