Lu Zijian, Fiehler Katja
Department of Experimental Psychology, Justus-Liebig-University, Giessen, Germany.
Department of Experimental Psychology, Justus-Liebig-University, Giessen, Germany; Center for Mind, Brain, and Behavior (CMBB), University of Marburg and Justus-Liebig University, Giessen, Germany.
Cortex. 2020 Apr;125:203-214. doi: 10.1016/j.cortex.2019.12.010. Epub 2020 Jan 7.
The 2-streams model of vision suggests that egocentric and allocentric reference frames are utilized by the dorsal and the ventral stream for real-time and memory-guided movements, respectively. Recent studies argue against such a strict functional distinction and suggest that real-time and memory-guided movements recruit the same spatial maps. In this study we focus on allocentric spatial coding and updating of targets by using landmark information in real-time and memory-guided reaching. We presented participants with a naturalistic scene which consisted of six objects on a table that served as potential reach targets. Participants were informed about the target object after scene encoding, and were prompted by a go cue to reach to its position. After target identification a brief air-puff was applied to the participant's right eye inducing an eye blink. During the blink the target object disappeared from the scene, and in half of the trials the remaining objects, that functioned as landmarks, were shifted horizontally in the same direction. We found that landmark shifts systematically influenced participants' reaching endpoints irrespective of whether the movements were controlled online based on available target information (real-time movement) or memory-guided based on remembered target information (memory-guided movement). Overall, the effect of landmark shift was stronger for memory-guided than real-time reaching. Our findings suggest that humans can encode and update reach targets in an allocentric reference frame for both real-time and memory-guided movements and show stronger allocentric coding when the movement is based on memory.
视觉的双流模型表明，以自我为中心和以他物为中心的参照系分别被背侧流和腹侧流用于实时运动和记忆引导运动。最近的研究反对这种严格的功能区分，并表明实时运动和记忆引导运动使用相同的空间地图。在本研究中，我们通过在实时和记忆引导的伸手动作中使用地标信息，聚焦于目标的以他物为中心的空间编码和更新。我们向参与者呈现了一个自然场景，场景中有六个物体放置在桌子上，这些物体可作为潜在的伸手目标。在场景编码后告知参与者目标物体，然后通过一个开始提示促使他们伸手去够目标物体的位置。在目标识别后，向参与者的右眼施加短暂的吹气，诱发眨眼。在眨眼期间，目标物体从场景中消失，并且在一半的试验中，作为地标的其余物体沿同一方向水平移动。我们发现，地标移动系统性地影响了参与者的伸手终点，无论这些动作是基于可用目标信息在线控制（实时运动）还是基于记忆的目标信息进行记忆引导（记忆引导运动）。总体而言，地标移动对记忆引导伸手的影响比对实时伸手的影响更强。我们的研究结果表明，人类能够在以他物为中心的参照系中对实时和记忆引导运动的伸手目标进行编码和更新，并且当运动基于记忆时，会表现出更强的以他物为中心的编码。
