Rottach K G, Das V E, Wohlgemuth W, Zivotofsky A Z, Leigh R J
Department of Neurology, Zentralklinikum Augsburg, 86009 Augsburg, Germany.
J Neurophysiol. 1998 Jun;79(6):2895-902. doi: 10.1152/jn.1998.79.6.2895.
Using the magnetic search coil technique to record eye and lid movements, we investigated the effect of voluntary blinks on horizontal saccades in five normal human subjects. The main goal of the study was to determine whether changes in the dynamics of saccades with blinks could be accounted for by a superposition of the eye movements induced by blinks as subjects fixated a stationary target and saccadic movements made without a blink. First, subjects made voluntary blinks as they fixed on stationary targets located straight ahead or 20 degrees to the right or left. They then made saccades between two continuously visible targets 20 or 40 degrees apart, while either attempting not to blink, or voluntarily blinking, with each saccade. During fixation of a target located straight ahead, blinks induced brief downward and nasalward deflections of eye position. When subjects looked at targets located at right or left 20 degrees, similar initial movements were made by four of the subjects, but the amplitude of the adducted eye was reduced by 65% and was followed by a larger temporalward movement. Blinks caused substantial changes in the dynamic properties of saccades. For 20 degrees saccades made with blinks, peak velocity and peak acceleration were decreased by approximately 20% in all subjects compared with saccades made without blinks. Blinks caused the duration of 20 degrees saccades to increase, on average, by 36%. On the other hand, blinks had only small effects on the gain of saccades. Blinks had little influence on the relative velocities of centrifugal versus centripetal saccades, and abducting versus adducting saccades. Three of five subjects showed a significantly increased incidence of dynamic overshoot in saccades accompanied by blinks, especially for 20 degrees movements. Taken with other evidence, this finding suggests that saccadic omnipause neurons are inhibited by blinks, which have longer duration than the saccades that company them. In conclusion, the changes in dynamic properties of saccades brought about by blinks cannot be accounted for simply by a summation of gaze perturbations produced by blinks during fixation and saccadic eye movements made without blinks. Our findings, especially the appearance of dynamic overshoots, suggest that blinks affect the central programming of saccades. These effects of blinks need to be taken into account during studies of the dynamic properties of saccades.
我们运用磁搜索线圈技术记录眼睛和眼睑运动，对5名正常人类受试者进行了研究，以探究自主眨眼对水平扫视的影响。本研究的主要目的是确定，当受试者注视静止目标且在不眨眼进行扫视运动时，眨眼引起的眼动叠加是否可以解释扫视动态变化。首先，受试者在注视正前方或左右20度位置的静止目标时进行自主眨眼。然后，他们在两个相距20度或40度且持续可见的目标之间进行扫视，每次扫视时要么尝试不眨眼，要么自主眨眼。在注视正前方的目标时，眨眼会引起眼睛位置短暂向下和向内偏移。当受试者注视左右20度位置的目标时，4名受试者出现了类似的初始运动，但内收眼的幅度降低了65%，随后出现了更大的向外运动。眨眼会导致扫视的动态特性发生显著变化。对于伴随眨眼进行的20度扫视，与不眨眼的扫视相比，所有受试者的峰值速度和峰值加速度均降低了约20%。眨眼使20度扫视的持续时间平均增加了36%。另一方面，眨眼对扫视增益的影响较小。眨眼对离心扫视与向心扫视、外展扫视与内收扫视的相对速度影响不大。5名受试者中有3名在伴随眨眼的扫视中出现动态过冲的发生率显著增加，尤其是20度的运动。结合其他证据，这一发现表明扫视全暂停神经元会受到眨眼抑制，而眨眼持续时间比与其相伴的扫视更长。总之，眨眼引起的扫视动态特性变化不能简单地通过眨眼在注视期间产生的注视扰动与不眨眼时的扫视眼动相加来解释。我们的研究结果，尤其是动态过冲的出现，表明眨眼会影响扫视的中枢编程。在研究扫视动态特性时，需要考虑眨眼的这些影响。
