Goossens H H, Van Opstal A J
Department of Medical Physics and Biophysics, University of Nijmegen, The Netherlands.
J Neurophysiol. 1997 Jul;78(1):533-8. doi: 10.1152/jn.1997.78.1.533.
Recent experiments have shown that the amplitude and direction of saccades evoked by microstimulation of the monkey superior colliculus depend systematically on the amplitude and direction of preceding visually guided saccades as well as on the postsaccade stimulation interval. The data are consistent with the hypothesis that an eye displacement integrator in the local feedback loop of the saccadic burst generator is gradually reset with a time constant of approximately 45 ms. If this is true, similar effects should occur during naturally evoked saccade sequences, causing systematic interval-dependent errors. To test this prediction in humans, saccades toward visual single- and double-step stimuli were elicited, and the properties of the second saccades were investigated as a function of the intersaccadic interval (ISI). In 15-20% of the saccadic responses, ISIs fell well below 100 ms. The errors of the second saccades were not systematically affected by the preceding primary saccade, irrespective of the ISI. Only a slight increase in the endpoint variability of second saccades was observed for the shortest ISIs. These results are at odds with the hypothesis that the putative eye displacement integrator has a reset time constant >10 ms. Instead, it is concluded that the signals involved in the internal feedback control of the saccadic burst generator reflect eye position and/or eye displacement accurately, irrespective of preceding eye movements.
最近的实验表明，对猴子上丘进行微刺激所诱发的扫视的幅度和方向，系统地取决于先前视觉引导扫视的幅度和方向以及扫视后刺激间隔。这些数据与以下假设一致：扫视爆发发生器局部反馈回路中的眼位移积分器以约45毫秒的时间常数逐渐重置。如果这是真的，那么在自然诱发的扫视序列中应该会出现类似的效应，导致系统性的间隔依赖性误差。为了在人类中测试这一预测，诱发了对视觉单步和双步刺激的扫视，并研究了第二个扫视的特性作为扫视间隔（ISI）的函数。在15%至20%的扫视反应中，ISI远低于100毫秒。第二个扫视的误差并未受到先前主扫视的系统性影响，无论ISI如何。仅在最短的ISI时，观察到第二个扫视的终点变异性略有增加。这些结果与假定的眼位移积分器具有大于10毫秒的重置时间常数这一假设不一致。相反，得出的结论是，扫视爆发发生器内部反馈控制中涉及的信号准确地反映了眼位置和/或眼位移，而与先前的眼动无关。
