Molenberghs Pascal, Gillebert Céline R, Peeters Ronald, Vandenberghe Rik
Cognitive Neurology Laboratory, Experimental Neurology Section, Katholieke Universiteit Leuven, Belgium.
J Neurosci. 2008 Mar 26;28(13):3359-73. doi: 10.1523/JNEUROSCI.5247-07.2008.
The parietal regions implicated in spatially selective attention differ between patient lesion studies and functional imaging of the intact brain. We aimed to resolve this discordance. In a voxel-based lesion-symptom mapping study in 20 ischemic stroke patients, we applied the same cognitive subtraction approach as in 23 healthy volunteers who underwent functional magnetic resonance imaging (fMRI) using identical tasks and stimuli. An instructive central cue directed attention to one visual quadrant. After a brief delay, a grating appeared in that quadrant together with an irrelevant grating in an uncued quadrant. Subjects had to discriminate the orientation of the grating in the cued quadrant. Patients with a right inferior parietal lesion were significantly more impaired during contralesional versus ipsilesional orienting when stimuli were bilateral and symmetrical than when stimuli occupied diagonally opposite quadrants or two quadrants within the same hemifield. In one area, the lesion-volume map overlapped with the activity map obtained in healthy volunteers: the lower bank of the middle third of the right intraparietal sulcus (IPS). In an additional 37 healthy fMRI subjects, we disentangled the effects of symmetry, bilaterality, and spatial configuration between stimuli on activity in the volume of overlap. Only the axis of configuration between stimuli had a significant effect, with highest activity when the configuration axis was horizontal. This constitutes converging evidence from patients and cognitively intact subjects that the lower bank of the middle third of the right IPS critically contributes to attentive selection between competing stimuli in a spatially anisotropic manner.
在患者病变研究和完整大脑的功能成像中，涉及空间选择性注意的顶叶区域有所不同。我们旨在解决这种不一致性。在一项对20名缺血性中风患者进行的基于体素的病变-症状映射研究中，我们采用了与23名健康志愿者相同的认知减法方法，这些志愿者使用相同的任务和刺激进行功能磁共振成像（fMRI）。一个指导性的中央线索将注意力引向一个视觉象限。短暂延迟后，该象限会出现一个光栅，同时在未提示的象限会出现一个无关的光栅。受试者必须辨别提示象限中光栅的方向。当刺激是双侧且对称时，与同侧定向相比，右侧顶叶下部病变的患者在对侧定向时明显受损更严重，而当刺激占据对角相对的象限或同一半视野内的两个象限时则不然。在一个区域，病变体积图与在健康志愿者中获得的活动图重叠：右侧顶内沟（IPS）中三分之一的下壁。在另外37名健康的fMRI受试者中，我们解析了刺激之间的对称性、双侧性和空间配置对重叠区域活动的影响。只有刺激之间的配置轴有显著影响，当配置轴为水平时活动最高。这构成了来自患者和认知健全受试者的汇聚证据，表明右侧IPS中三分之一的下壁以空间各向异性的方式对竞争性刺激之间的注意力选择起关键作用。
