School of Psychology, University of Glasgow, Glasgow G12 8QB, Scotland, UK.
Neuropsychologia. 2012 May;50(6):1018-28. doi: 10.1016/j.neuropsychologia.2011.09.030. Epub 2011 Sep 22.
It is well established that patients with hemispatial neglect present with severe visuospatial impairments, but studies that have investigated visuomotor control directly have revealed diverging results, with some investigations finding impairments mirroring the perceptual difficulties of these patients, while others have shown that such neglect patients perform relatively better in action tasks. In this review we attempt to reconcile these diverging findings, addressing differences in the type of visuomotor tasks studied but also highlighting the diverging neuroanatomy that seems to be driving the differences in performance. We argue that there are different types of actions and that these in turn depend on different cortical networks (Goodale, Westwood, & Milner, 2004; Milner & Goodale, 2006). Patients with visuospatial neglect, in contrast to patients with optic ataxia, are relatively unimpaired at performing target-directed tasks even towards stimuli located in their 'neglected' field. We relate these findings to the view that for the on-line guidance of action, spatial information is coded in egocentric coordinates and depends on the visuomotor networks of the visual dorsal stream. Furthermore, based on recent lesion-symptom mapping studies, we postulate that deficits in on-line actions that are observed after right-brain damage are associated with damage to the visuomotor control network, in particular with damage to the basal ganglia, frontal and parieto-occipital regions. On the other hand, clear neglect-specific deficits emerge when the action is off-line and not directly target-driven, thus requiring relational metrics or scene-based coordinates (as is the case for example in delayed and mirrored (anti-pointing) reaches). We review recent studies that support our argument that such deficits in off-line actions are associated with damage to occipito-temporal and parahippocampal cortex, perhaps as part of the ventral visual stream or areas where information from the two visual streams is combined.
人们已经充分认识到，偏侧空间忽略症患者存在严重的视空间障碍，但直接研究运动知觉控制的研究结果却存在分歧，一些研究发现，这些患者的知觉障碍与运动知觉控制的损伤相一致，而另一些研究则表明，此类忽略症患者在动作任务中的表现相对较好。在这篇综述中，我们试图调和这些分歧的发现，既解决了所研究的运动知觉任务类型的差异，也强调了似乎导致表现差异的不同神经解剖结构。我们认为，存在不同类型的动作，而这些动作又取决于不同的皮质网络（Goodale、Westwood 和 Milner，2004；Milner 和 Goodale，2006）。与视动性共济失调患者不同，偏侧空间忽略症患者在执行目标导向任务时，即使面对位于其“忽略”视野内的刺激，也相对不受影响。我们将这些发现与以下观点联系起来，即对于运动的在线指导，空间信息以自我中心坐标编码，并且依赖于视觉背侧流的运动视觉网络。此外，基于最近的损伤-症状映射研究，我们假设，在右大脑损伤后观察到的在线动作缺陷与运动控制网络的损伤有关，特别是与基底节、额叶和顶枕叶区域的损伤有关。另一方面，当动作是离线的且不是直接目标驱动时，就会出现明确的忽略特异性缺陷，因此需要关系度量或基于场景的坐标（例如，在延迟和镜像（反向）伸手任务中）。我们综述了最近的研究，这些研究支持了我们的观点，即此类离线动作缺陷与枕颞叶和海马旁回的损伤有关，可能是作为腹侧视觉流或两个视觉流信息整合的区域的一部分。
