Kelly Shane, Zhou Weiwei, Bansal Sonia, Peterson Matthew S, Joiner Wilsaan M
Department of Psychology, George Mason University, Fairfax, VA 22030, United States.
Department of Bioengineering, George Mason University, Fairfax, VA 22030, United States; Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA 95616, United States.
Vision Res. 2019 Oct;163:1-13. doi: 10.1016/j.visres.2019.08.003. Epub 2019 Aug 28.
The double-step paradigm investigates the characteristics of planning and execution when the motor system must rapidly adjust for a new goal location. Studies have provided detailed temporal information based on the duration available for the motor system to prepare a new movement trajectory (here referred to as re-preparation time). However, previous work has largely examined single displacement sizes, limiting the spatiotemporal understanding of movement planning and execution. The lack of a description of this behavioral timecourse across increasing displacement sizes is true for saccades, rapid eye movements that redirect the fovea. Furthermore, during the double-step paradigm, the primary saccade often fails to accurately foveate the final target location and a secondary saccade brings the target onto the fovea. However, it is also unknown how this compensation is concurrently modified with the exposure duration and displacement of the movement goal. Here, we examined the amount of time required to change the initial saccade direction to a new target location for relatively small (20°, 30°, and 40°) and large (60° and 90°) target spatial separations. Interestingly, we found a clear relationship between the saccade direction and the amount of time allowed to redirect the movement; across separations, intermediate saccades occurred when approximately 60-140 ms was available to readjust the movement plan. Additionally, there was a consistent relationship between the timing of the secondary saccade and the re-preparation time across jump sizes, suggesting that concurrent movement correction planning was dependent on the amount of exposure to the final movement goal.
双步范式研究了运动系统必须快速调整以适应新目标位置时的计划和执行特征。研究已经基于运动系统准备新运动轨迹的可用持续时间（这里称为重新准备时间）提供了详细的时间信息。然而，先前的工作大多研究了单一的位移大小，限制了对运动计划和执行的时空理解。对于扫视（即重新定位中央凹的快速眼动）而言，缺乏对随着位移大小增加的这种行为时间进程的描述。此外，在双步范式中，初级扫视常常无法准确地使中央凹对准最终目标位置，而次级扫视会将目标带到中央凹上。然而，这种补偿如何随着运动目标的暴露持续时间和位移同时改变也是未知的。在这里，我们研究了将初始扫视方向改变为相对较小（20°、30°和40°）和较大（60°和90°）目标空间间隔的新目标位置所需的时间量。有趣的是，我们发现扫视方向与允许重新定向运动的时间量之间存在明显的关系；在不同间隔中，当有大约60 - 140毫秒可用于重新调整运动计划时会出现中间扫视。此外，次级扫视的时间与不同跳跃大小下的重新准备时间之间存在一致的关系，这表明同时进行的运动校正计划取决于对最终运动目标的暴露量。
