Van der Stigchel Stefan, van Zoest Wieske, Theeuwes Jan, Barton Jason J S
Vrije Universiteit, Amsterdam, the Netherlands.
J Cogn Neurosci. 2008 Nov;20(11):2025-36. doi: 10.1162/jocn.2008.20145.
There is evidence that some visual information in blind regions may still be processed in patients with hemifield defects after cerebral lesions ("blindsight"). We tested the hypothesis that, in the absence of retinogeniculostriate processing, residual retinotectal processing may still be detected as modifications of saccades to seen targets by irrelevant distractors in the blind hemifield. Six patients were presented with distractors in the blind and intact portions of their visual field and participants were instructed to make eye movements to targets in the intact field. Eye movements were recorded to determine if blind-field distractors caused deviation in saccadic trajectories. No deviation was found in one patient with an optic chiasm lesion, which affect both retinotectal and retinogeniculostriate pathways. In five patients with lesions of the optic radiations or the striate cortex, the results were mixed, with two of the five patients showing significant deviations of saccadic trajectory away from the "blind" distractor. In a second experiment, two of the five patients were tested with the target and the distractor more closely aligned. Both patients showed a "global effect," in that saccades deviated toward the distractor, but the effect was stronger in the patient who also showed significant trajectory deviation in the first experiment. Although our study confirms that distractor effects on saccadic trajectory can occur in patients with damage to the retinogeniculostriate visual pathway but preserved retinotectal projections, there remain questions regarding what additional factors are required for these effects to manifest themselves in a given patient.
有证据表明，脑部病变后出现半视野缺损的患者（“盲视”），其盲区中的一些视觉信息可能仍会被处理。我们检验了这样一个假设：在不存在视网膜 - 膝状体 - 纹状体系加工的情况下，残余的视网膜 - 顶盖加工仍可能被检测到，表现为盲半视野中无关干扰物对看向目标的扫视运动产生改变。给6名患者的视野盲区和正常区域呈现干扰物，并指示参与者对正常视野中的目标进行眼动。记录眼动情况以确定盲区干扰物是否会导致扫视轨迹偏差。在一名视交叉病变患者中未发现偏差，该病变影响了视网膜 - 顶盖和视网膜 - 膝状体 - 纹状体系两条通路。在5名视辐射或纹状皮质病变患者中，结果不一，5名患者中有2名的扫视轨迹出现明显偏离“盲”干扰物的情况。在第二个实验中，对5名患者中的2名进行测试，使目标和干扰物的位置更接近对齐。两名患者均表现出“整体效应”，即扫视运动偏向干扰物，但在第一个实验中也出现明显轨迹偏差的患者中，这种效应更强。尽管我们的研究证实，在视网膜 - 膝状体 - 纹状体系视觉通路受损但视网膜 - 顶盖投射保留的患者中，干扰物会对扫视轨迹产生影响，但对于这些效应在特定患者中显现还需要哪些额外因素，仍存在疑问。
