Institute of Psychology, University of Münster, Germany; Otto-Creutzfeldt-Center for Cognitive and Behavioral Neuroscience, University of Münster, Germany.
Institute of Psychology, University of Münster, Germany; Otto-Creutzfeldt-Center for Cognitive and Behavioral Neuroscience, University of Münster, Germany.
Prog Neurobiol. 2024 Mar;234:102576. doi: 10.1016/j.pneurobio.2024.102576. Epub 2024 Feb 1.
The visual system represents objects in a lateralized manner, with contralateral cortical hemispheres responsible for left and right visual hemifields. This organization extends to visual short-term memory (VSTM), as evidenced by electrophysiological indices of VSTM maintenance: contralateral delay activity (CDA) and alpha-band lateralization. However, it remains unclear if VSTM represents object locations in gaze-centered (retinotopic) or screen-centered (spatiotopic) coordinates, especially after eye movements. In two experiments, participants encoded the colors of target objects and made a lateral saccade during the maintenance interval, thereby shifting the object's location on the retina. A non-lateralized probe stimulus was then presented at the new fixation for a change detection task. The CDA maintained lateralization towards the target's original retinotopic location, unaffected by subsequent saccades, and did not invert polarity even when a saccade brought that location into the opposite hemifield. We also found conventional alpha lateralization towards the target's location before a saccade. After a saccade, however, alpha was lateralized towards the screen center regardless of the target's original location, even in a control condition without any memory requirements. This suggests that post-saccadic alpha-band lateralization reflects attentional processes unrelated to memory, while pre- and post-saccade CDA reflect VSTM maintenance in a retinotopic reference frame.
视觉系统以偏侧化的方式表示物体，对侧大脑皮层半球负责左、右眼视觉半视野。这种组织延伸到视觉短期记忆（VSTM），这可以通过 VSTM 维持的电生理指标来证明：对侧延迟活动（CDA）和 alpha 波段侧化。然而，VSTM 是否以凝视中心（视网膜）或屏幕中心（空间）坐标来表示物体位置，尤其是在眼动之后，仍不清楚。在两项实验中，参与者在维持间隔期间编码目标物体的颜色并进行横向扫视，从而改变物体在视网膜上的位置。然后在新注视点呈现非侧化的探测刺激，以进行变化检测任务。CDA 保持朝向目标原始视网膜位置的侧化，不受随后扫视的影响，即使扫视将该位置带入对侧视野，其极性也不会反转。我们还发现，在扫视之前，alpha 波向目标位置偏侧化。然而，扫视后，alpha 波无论目标的原始位置如何，都偏向屏幕中心，即使在没有任何记忆要求的对照条件下也是如此。这表明，扫视后 alpha 波段侧化反映了与记忆无关的注意力过程，而扫视前后的 CDA 反映了在视网膜参考系中 VSTM 的维持。
