Neurology Clinic, University Hospital Rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany; Clinical Neuropsychology Research Group (EKN), Hospital München-Bogenhausen, Dachauer Str. 164, D-80992 Munich, Germany.
Department of Psychology, University of Oregon, 1227 University of Oregon, Eugene, OR 97403-1227, USA; Clinical Neuropsychology Research Group (EKN), Hospital München-Bogenhausen, Dachauer Str. 164, D-80992 Munich, Germany.
Neuropsychologia. 2011 Apr;49(5):914-923. doi: 10.1016/j.neuropsychologia.2011.02.018. Epub 2011 Feb 17.
The prediction of object weight from its size is an important prerequisite of skillful object manipulation. Grip and load forces anticipate object size during early phases of lifting an object. A mismatch between predicted and actual weight when two different sized objects have the same weight results in the size-weight illusion (SWI), the small object feeling heavier. This study explores whether lateralized brain lesions in patients with or without apraxia alter the size-weight illusion and impair anticipatory finger force scaling. Twenty patients with left brain damage (LBD, 10 with apraxia, 10 without apraxia), ten patients with right brain damage (RBD), and matched control subjects lifted two different-sized boxes in alternation. All subjects experienced a similar size-weight illusion. The anticipatory force scaling of all groups was in correspondence with the size cue: higher forces and force rates were applied to the big box and lower forces and force rates to the small box during the first lifts. Within few lifts, forces were scaled to actual object weight. Despite the lack of significant differences at group level, 5 out of 20 LBD patients showed abnormal predictive scaling of grip forces. They differed from the LBD patients with normal predictive scaling by a greater incidence of posterior occipito-parietal lesions but not by a greater incidence of apraxia. The findings do not support a more general role for the motor-dominant left hemisphere, or an influence of apraxia per se, in the scaling of finger force according to object properties. However, damage in the vicinity of the parietal-occipital junction may be critical for deriving predictions of weight from size.
从物体大小预测其重量是熟练操纵物体的重要前提。在提起物体的早期阶段，握力和负载力会预测物体的大小。当两个不同大小的物体重量相同时，预测重量和实际重量之间的不匹配会导致大小重量错觉（SWI），即小物体感觉更重。本研究探讨了患有或不患有失用症的患者的侧化脑损伤是否会改变大小重量错觉并损害预期手指力缩放。20 名左脑损伤患者（LBD，10 名失用症患者，10 名无失用症患者）、10 名右脑损伤患者（RBD）和匹配的对照组患者交替举起两个不同大小的盒子。所有受试者都经历了相似的大小重量错觉。所有组的预期力缩放都与大小提示相对应：在第一次提起时，大盒子应用更高的力和力率，小盒子应用更低的力和力率。在几次提起后，力被缩放至实际物体重量。尽管在组水平上没有显著差异，但 20 名 LBD 患者中的 5 名显示出异常的握力预测缩放。他们与具有正常预测缩放的 LBD 患者的不同之处在于后枕顶叶病变的发生率更高，但失用症的发生率没有更高。研究结果不支持运动优势的左半球在根据物体属性缩放手指力方面发挥更普遍的作用，也不支持失用症本身的影响。然而，顶枕交界附近的损伤可能对从大小推断重量的预测至关重要。
