McMaster Integrative Neuroscience Discovery and Study (MiNDS), Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
Exp Brain Res. 2011 Jul;212(3):457-69. doi: 10.1007/s00221-011-2752-6. Epub 2011 Jun 10.
Recent investigations have revealed the kinematics of horizontal saccades are less variable near the end of the trajectory than during the course of execution. Converging evidence indicates that oculomotor networks use online sensorimotor feedback to correct for initial trajectory errors. It is also known that oculomotor networks express saccadic corrections with decreased efficiency when responses are made toward memorized locations. The present research investigated whether repetitive motor timekeeping influences online feedback-based corrections in predictive saccades. Predictive saccades are a subclass of memory-guided saccades and are observed when one makes series of timed saccades. We hypothesized that cueing predictive saccades in a sequence would facilitate the expression of trajectory corrections. Seven participants produced a number of single unpaced, visually guided saccades, and also sequences of timed predictive saccades. Kinematic and trajectory variability were used to measure the expression of online saccadic corrections at a number of time indices in saccade trajectories. In particular, we estimated the minimum time required to implement feedback-based corrections, which was consistently 37 ms. Our observations demonstrate that motor commands in predictive memory-guided saccades can be parameterized by spatial working memory and retain the accuracy of online trajectory corrections typically associated with visually guided behavior. In contrast, untimed memory-guided saccades exhibited diminished kinematic evidence for online corrections. We conclude that motor timekeeping and sequencing contributed to efficient saccadic corrections. These results contribute to an evolving view of the interactions between motor planning and spatial working memory, as they relate to oculomotor control.
最近的研究揭示了水平眼跳的运动学特征，即在轨迹末端比在执行过程中变化较小。越来越多的证据表明，眼球运动网络利用在线感觉运动反馈来纠正初始轨迹误差。众所周知，当朝向记忆位置做出反应时，眼球运动网络会以降低效率的方式表达眼跳校正。本研究探讨了重复运动计时是否会影响预测性眼跳中的在线基于反馈的校正。预测性眼跳是记忆引导性眼跳的一个子类，当人们进行一系列定时眼跳时就会观察到。我们假设在序列中提示预测性眼跳会促进轨迹校正的表达。七名参与者进行了一系列无定时、视觉引导的单次眼跳，以及定时预测性眼跳序列。在眼跳轨迹的多个时间指数上，使用运动学和轨迹可变性来衡量在线眼跳校正的表达。特别是，我们估计了实施基于反馈的校正所需的最小时间，这一时间始终为 37 毫秒。我们的观察表明，在预测性记忆引导的眼跳中，运动指令可以被空间工作记忆参数化，并保留与视觉引导行为相关的在线轨迹校正的准确性。相比之下，无定时的记忆引导眼跳在线校正的运动学证据明显减少。我们得出结论，运动计时和排序有助于高效的眼跳校正。这些结果有助于形成运动规划和空间工作记忆之间相互作用的新观点，因为它们与眼球运动控制有关。
