Université Grenoble Alpes, CNRS, LPNC UMR 5105, Grenoble, France.
Univ. Lille, CNRS, CHU Lille, UMR 9193, SCALab - Sciences Cognitives et Sciences Affectives, F-59000 Lille, France.
Neuropsychologia. 2018 Apr;112:125-134. doi: 10.1016/j.neuropsychologia.2018.03.007. Epub 2018 Mar 6.
Visual extinction, a parietal syndrome in which patients exhibit perceptual impairments when two objects are simultaneously presented in the visual field, is reduced when objects are correctly positioned for action, indicating that action helps patients' visual attention. Similarly, healthy individuals make faster action decisions on object pairs that appear in left/right standard co-location for actions in comparison to object pairs that appear in a mirror location, a phenomenon called the paired-object affordance effect. However, the neural locus of such effect remains debated and may be related to the activity of ventral or dorsal brain regions. The present fMRI study aims at determining the neural substrates of the paired-object affordance effect. Fourteen right-handed participants made decisions about semantically related (i.e. thematically related and co-manipulated) and unrelated object pairs. Pairs were either positioned in a standard location for a right-handed action (with the active object - lid - in the right visual hemifield, and the passive object - pan - in the left visual hemifield), or in the reverse location. Behavioral results showed a suppression of the observed cost of correctly positioning related pairs for action when performing action decisions (deciding if the two objects are usually used together), but not when performing contextual decisions (deciding if the two objects are typically found in the kitchen). Anterior regions of the dorsal stream (e.g. supplementary motor area) responded to inadequate object co-positioning for action, but only when the perceptual task required action decisions. In the ventral cortex, the left lateral occipital complex showed increased activation for objects correctly positioned for action in all conditions except when neither task demands nor object relatedness was relevant for action. Thus, fMRI results demonstrated a joint contribution of ventral and dorsal cortical streams to the paired-affordance effect. They further suggest that this contribution may depend on contextual situations and task demands, in line with flexible views of affordance evocation.
视觉消失，一种顶叶综合征，患者在视野中同时呈现两个物体时表现出知觉障碍，当物体被正确定位用于行动时，这种障碍会减轻，这表明行动有助于患者的视觉注意力。同样，健康个体在进行左/右标准共定位的物体对进行动作决策时比在镜像位置出现的物体对做出更快的动作决策，这种现象称为成对物体可供性效应。然而，这种效应的神经定位仍然存在争议，可能与腹侧或背侧脑区的活动有关。本 fMRI 研究旨在确定成对物体可供性效应的神经基础。14 名右利手参与者对语义相关（即主题相关和共同操作）和不相关的物体对做出决策。物体对要么位于适合右手动作的标准位置（主动物体-盖子-在右视觉半视野，被动物体-平底锅-在左视觉半视野），要么位于相反的位置。行为结果表明，在执行动作决策（判断两个物体是否通常一起使用）时，正确定位相关物体对动作的观察成本受到抑制，但在执行上下文决策（判断两个物体是否通常在厨房中找到）时则不受抑制。背侧流的前区域（例如补充运动区）对动作中物体的不适当共定位有反应，但仅在感知任务需要动作决策时才有反应。在腹侧皮层中，左侧外侧枕叶复合体在所有条件下对正确定位用于动作的物体显示出增加的激活，除了在既不要求任务也不要求物体相关性用于动作的情况下。因此，fMRI 结果表明，腹侧和背侧皮质流对成对可供性效应有共同贡献。它们进一步表明，这种贡献可能取决于上下文情况和任务需求，符合可供性唤起的灵活观点。
