Laboratoire Psychologie de la Perception, Université Paris Descartes & CNRS, 45 rue des Saints-Pères 75006 Paris, France.
Laboratoire Psychologie de la Perception, Université Paris Descartes & CNRS, 45 rue des Saints-Pères 75006 Paris, France; Laboratoire de Neurosciences Cognitives (LNC), Département d'Etudes Cognitives, INSERM U960, Ecole Normale Supérieure, PSL Research University, 75005 Paris, France; Institut Jean Nicod, Département d'Etudes Cognitives, CNRS UMR8129, Ecole Normale Supérieure, PSL Research University, 75005 Paris, France.
Brain Stimul. 2018 Mar-Apr;11(2):390-399. doi: 10.1016/j.brs.2017.11.019. Epub 2017 Nov 29.
Saccadic eye movements change the retinal location of visual objects, but we do not experience the visual world as constantly moving, we perceive it as seamless and stable. This visual stability may be achieved by an internal or efference copy of each saccade that, combined with the retinal information, allows the visual system to cancel out or ignore the self-caused retinal motion.
The current study investigated the underlying brain mechanisms responsible for visual stability in humans with online transcranial magnetic stimulation (TMS).
We used two classic tasks that measure efference copy: the double-step task and the in-flight displacement task. The double-step task requires subjects to make two memory-guided saccades, the second of which depends on an accurate internal copy of the first. The in-flight displacement task requires subjects to report the relative location of a (possibly displaced) target across a saccade. In separate experimental sessions, subjects participated in each task while we delivered online 3-pulse TMS over frontal eye fields (FEF), posterior parietal cortex, or vertex. TMS was contingent on saccade execution.
Second saccades were not disrupted in the double-step task, but surprisingly, TMS over FEF modified the metrics of the ongoing saccade. Spatiotopic performance in the in-flight displacement task was altered following TMS over parietal cortex, but not FEF or vertex.
These results suggest that TMS disrupted eye-centered position coding in the parietal cortex. Trans-saccadic correspondence, and visual stability, may therefore causally depend on parietal maps.
扫视眼动改变了视觉物体在视网膜上的位置，但我们并没有感觉到视觉世界在不断移动，而是将其视为无缝和稳定的。这种视觉稳定性可能是通过每个扫视的内部或传出副本实现的，该副本与视网膜信息结合使用，可以使视觉系统消除或忽略自身引起的视网膜运动。
本研究使用在线经颅磁刺激（TMS）研究了负责人类视觉稳定性的大脑机制。
我们使用了两种经典的任务来测量传出副本：双步任务和飞行中位移任务。双步任务要求受试者进行两次记忆引导的扫视，第二次扫视依赖于第一次扫视的准确内部副本。飞行中位移任务要求受试者报告在扫视过程中（可能发生位移的）目标的相对位置。在单独的实验会议中，当我们在额眼区（FEF）、顶后皮质或头顶施加在线 3 脉冲 TMS 时，受试者参加了每个任务。TMS 取决于扫视执行情况。
在双步任务中，第二次扫视没有受到干扰，但令人惊讶的是，FEF 上的 TMS 改变了正在进行的扫视的度量。在飞行中位移任务中的空间位置表现在顶后皮质 TMS 后发生改变，但 FEF 或头顶 TMS 则没有。
这些结果表明，TMS 破坏了顶后皮质中的眼中心位置编码。因此，跨扫视对应和视觉稳定性可能取决于顶叶图谱。
