Goldring J E, Dorris M C, Corneil B D, Ballantyne P A, Munoz D P
Department of Physiology, Queen's University, Kingston, Ontario, Canada.
Exp Brain Res. 1996 Sep;111(1):68-78. doi: 10.1007/BF00229557.
We studied the characteristics of combined eye-head gaze shifts in human subjects to determine whether they used similar strategies when looking at visual (V), auditory (A), and combined (V + A) targets located at several target eccentricities along the horizontal meridian. Subjects displayed considerable variability in the combinations of eye and head movement used to orient to the targets, ranging from those who always aligned their head close to the target, to those who relied predominantly on eye movements and only moved their head when the target was located beyond the limits of ocular motility. For a given subject, there was almost no variability in the amount of eye and head movement in the three target conditions (V, A, V + A). The time to initiate a gaze shift was influenced by stimulus modality and eccentricity. Auditory targets produced the longest latencies when located centrally (less than 20 degrees eccentricity), whereas visual targets evoked the longest latencies when located peripherally (greater than 40 degrees eccentricity). Combined targets (V + A) elicited the shortest latency reaction times at all eccentricities. The peak velocity of gaze shifts was also affected by target modality. At eccentricities between 10 and 30 degrees, peak gaze velocity was greater for movements to visual targets than for movements to auditory targets. Movements to the combined target were of comparable speed with movements to visual targets. Despite the modality-specific differences in reaction latency and peak gaze velocity, the consistency of combinations of eye and head movement within subjects suggests that visual and auditory signals are remapped into a common reference frame for controlling orienting gaze shifts. A likely candidate is the deeper layers of the superior colliculus, because visual and auditory signals converge directly onto the neurons projecting to the eye and head premotor centers.
我们研究了人类受试者联合眼-头注视转移的特征，以确定他们在注视沿水平子午线位于几个不同偏心度的视觉（V）、听觉（A）和联合（V+A）目标时是否使用相似的策略。受试者在用于朝向目标的眼动和头动组合方面表现出相当大的变异性，从那些总是将头部靠近目标对齐的人，到那些主要依赖眼动且仅在目标位于眼动范围之外时才移动头部的人。对于给定的受试者，在三种目标条件（V、A、V+A）下，眼动和头动的量几乎没有变异性。启动注视转移的时间受刺激模式和偏心度的影响。听觉目标位于中央（偏心度小于20度）时产生最长的潜伏期，而视觉目标位于周边（偏心度大于40度）时诱发最长的潜伏期。联合目标（V+A）在所有偏心度下都引发最短的潜伏期反应时间。注视转移的峰值速度也受目标模式的影响。在10至30度的偏心度之间，朝向视觉目标的注视峰值速度大于朝向听觉目标的注视峰值速度。朝向联合目标的移动速度与朝向视觉目标的移动速度相当。尽管在反应潜伏期和注视峰值速度方面存在模式特异性差异，但受试者内眼动和头动组合的一致性表明，视觉和听觉信号被重新映射到一个共同的参考框架中，以控制定向注视转移。一个可能的候选部位是上丘的深层，因为视觉和听觉信号直接汇聚到投射到眼和头运动前区中心的神经元上。
