Breznen B, Lu S M, Gnadt J W
Department of Neurobiology and Behavior, State University of New York at Stony Brook 11794, USA.
Exp Brain Res. 1996 Oct;111(3):337-44. doi: 10.1007/BF00228723.
We used prolonged stimulation of the monkey superior colliculus to elicit staircase eye movements. By changing the parameters of the stimulating current we were able to obtain movements with different dynamics. An increase in the current frequency resulted in the shortening of the intersaccadic interval and a decrease of the amplitudes in the staircase. In cases of high stimulation, after an initial saccade of fixed metrics, the eyes moved in an apparently smooth fashion. The movement was conjugate and in the same direction as the first saccade. By analyzing the velocity trace we found that the movement consisted of a chain of small saccades, each of which started before the previous one ended. We conducted a quantitative analysis of the staircase movements including the cases of apparently smooth movement of the eyes. We conclude that all of the movements elicited by prolonged SC stimulation were generated by the saccadic feedback circuitry. The dynamic profiles of the elicited movements changed continuously with the stimulating current parameters. On one end of the continuum we observed the classically, described staircase movements with individual movements separated in time. On the other end of the continuum we saw the apparent smooth movement as the limit case produced by high stimulation of the SC.
我们通过对猴子上丘进行长时间刺激来诱发阶梯式眼球运动。通过改变刺激电流的参数，我们能够获得具有不同动力学特征的运动。电流频率增加会导致扫视间隔缩短以及阶梯式运动中幅度减小。在高刺激情况下，在最初具有固定指标的扫视之后，眼睛以明显平滑的方式移动。该运动是共轭的，并且与第一个扫视方向相同。通过分析速度轨迹，我们发现该运动由一系列小扫视组成，每个小扫视都在前一个扫视结束之前开始。我们对阶梯式运动进行了定量分析，包括眼睛明显平滑运动的情况。我们得出结论，长时间上丘刺激引发的所有运动都是由扫视反馈回路产生的。所引发运动的动态特征随刺激电流参数不断变化。在连续体的一端，我们观察到经典描述的阶梯式运动，其中各个运动在时间上是分开的。在连续体的另一端，我们将明显平滑的运动视为上丘高刺激产生的极限情况。
