Huberle Elisabeth, Karnath Hans-Otto
Section Neuropsychology, Department of Cognitive Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler-Strasse 3, D-72076 Tübingen, Germany.
Neuropsychologia. 2006;44(6):905-11. doi: 10.1016/j.neuropsychologia.2005.08.013. Epub 2005 Oct 14.
Simultanagnosia is a rare deficit that impairs individuals in perceiving several objects at the same time. It is usually observed following bilateral parieto-occipital brain damage. Despite the restrictions in perceiving the global aspect of a scene, processing of individual objects remains unaffected. The mechanisms underlying simultanagnosia are not well understood. Previous findings indicated that the integration of multiple objects into a holistic representation of the environment is not impossible per se, but might depend on the spatial relationship between individual objects. The present study examined the influence of inter-element distances between individual objects on the recognition of global shapes in two patients with simultanagnosia. We presented Navon hierarchical letter stimuli with different inter-element distances between letters at the Local Scale. Improved recognition at the Global Scale was observed in both patients by reducing the inter-element distance. Global shape recognition in simultanagnosia thus seems to be modulated by the spatial distance of local elements and does not appear to be an all-or-nothing phenomenon depending on spatial continuity. The findings seem to argue against a deficit in visual working memory capacity as the primary deficit in simultanagnosia. However, further research is necessary to investigate alternative interpretations.
同时失认症是一种罕见的缺陷，它会损害个体同时感知多个物体的能力。通常在双侧顶枕叶脑损伤后出现。尽管在感知场景的整体方面存在限制，但对单个物体的处理仍未受影响。同时失认症背后的机制尚未完全了解。先前的研究结果表明，将多个物体整合为环境的整体表征本身并非不可能，但可能取决于单个物体之间的空间关系。本研究考察了单个物体之间的元素间距离对两名患有同时失认症患者识别整体形状的影响。我们在局部尺度上呈现了字母间元素间距离不同的纳冯层级字母刺激。通过减小元素间距离，两名患者在整体尺度上的识别能力均得到了改善。因此，同时失认症中的整体形状识别似乎受到局部元素空间距离的调节，并且似乎不是一种取决于空间连续性的非此即彼的现象。这些发现似乎与视觉工作记忆容量缺陷是同时失认症的主要缺陷这一观点相悖。然而，需要进一步的研究来探究其他解释。
