Psychology Department, University of Oregon, Eugene, OR 97403-1227, USA.
Exp Brain Res. 2012 Aug;221(1):51-8. doi: 10.1007/s00221-012-3146-0. Epub 2012 Jun 27.
This study was undertaken to determine if target predictability could modulate saccadic planning and timing at the level of the frontal eye fields (FEF). To this end, healthy participants performed two gap saccade tasks in which the targets were displaced left or right of the midline in either a predictable or a random fashion. Additionally, half of the participants were informed about this manipulation. Single pulse transcranial magnetic stimulation (TMS) was applied to the left FEF before, during, or after the target onset. We examined both the saccade latency and the frequency of multiple saccades (MS) (i.e., saccades that covered <90 % of the distance to the target and were subsequently followed by a corrective saccade). Findings revealed that saccadic reaction times were quickest to the more predictable target side and also confirmed that MS were released more quickly than single saccades. Further, the frequency of MS differed between target locations; higher frequencies of MS were found on the unpredictable side, showing more vulnerability to TMS disruption. In conclusion, we have demonstrated that target predictability modulates saccade planning and that this modulation takes place at least in part in the FEF. The influence of FEF in these processes is observed both in the latencies with which saccades are executed and in the timing and characteristics of the multiple saccades that are observed under different task constraints. Finally, the timing of the FEF contribution also appears to be influenced by the manipulation of target predictability. Each of these observations serves to further clarify the role of the human FEF in saccade planning.
本研究旨在确定目标可预测性是否可以调节额眼区（FEF）水平的眼跳计划和定时。为此，健康参与者执行了两种间隙眼跳任务，其中目标在中线的左侧或右侧以可预测或随机的方式移位。此外，一半的参与者被告知这种操作。在目标出现之前、期间或之后，将单个脉冲经颅磁刺激（TMS）施加于左侧 FEF。我们检查了眼跳潜伏期和多次眼跳（MS）的频率（即覆盖目标距离 <90%的眼跳，随后被纠正性眼跳所跟随）。研究结果表明，更可预测的目标侧的眼跳反应时间最快，并且还证实 MS 比单次眼跳释放得更快。此外，MS 的频率在目标位置之间有所不同；在不可预测的一侧发现了更高频率的 MS，表明对 TMS 干扰的敏感性更高。总之，我们已经证明目标可预测性调节眼跳计划，并且这种调节至少部分发生在 FEF 中。在执行眼跳的潜伏期以及在不同任务约束下观察到的多次眼跳的定时和特征方面，都观察到了 FEF 在这些过程中的影响。最后，FEF 贡献的定时似乎也受到目标可预测性的操作的影响。这些观察结果中的每一个都有助于进一步阐明人类 FEF 在眼跳计划中的作用。
