Garg Arun, Schwartz Daniel, Stevens Alexander A
Department of Psychiatry, Oregon Health Science University, Portland, OR 97239, USA.
Neuropsychologia. 2007 Jun 11;45(10):2307-21. doi: 10.1016/j.neuropsychologia.2007.02.015. Epub 2007 Feb 25.
What happens in vision-related cortical areas when congenitally blind (CB) individuals orient attention to spatial locations? Previous neuroimaging of sighted individuals has found overlapping activation in a network of frontoparietal areas including frontal eye fields (FEF), during both overt (with eye movement) and covert (without eye movement) shifts of spatial attention. Since voluntary eye movement planning seems irrelevant in CB, their FEF neurons should be recruited for alternative functions if their attentional role in sighted individuals is only due to eye movement planning. Recent neuroimaging of the blind has also reported activation in medial occipital areas, normally associated with visual processing, during a diverse set of non-visual tasks, but their response to attentional shifts remains poorly understood. Here, we used event-related fMRI to explore FEF and medial occipital areas in CB individuals and sighted controls with eyes closed (SC) performing a covert attention orienting task with endogenous verbal cues and spatialized auditory targets. We found robust stimulus-locked FEF activation of all CB subjects, similar to and stronger than in SC, suggesting that FEF plays a role in endogenous orienting of covert spatial attention even in individuals in whom voluntary eye movements are irrelevant. We also found robust activation in bilateral medial occipital cortex in CB but not in SC subjects. The response decreased below baseline following endogenous verbal cues but increased following auditory targets, suggesting that the medial occipital area in CB does not directly engage during cued orienting of attention but may be recruited for processing of spatialized auditory targets.
当先天性失明（CB）个体将注意力定向到空间位置时，与视觉相关的皮层区域会发生什么？先前对有视力个体的神经成像研究发现，在空间注意力的明显（伴随眼球运动）和隐蔽（不伴随眼球运动）转移过程中，包括额叶眼区（FEF）在内的额顶叶区域网络存在重叠激活。由于自愿眼球运动计划在CB个体中似乎无关紧要，如果FEF神经元在有视力个体中的注意力作用仅仅是由于眼球运动计划，那么它们应该被用于其他功能。最近对盲人的神经成像研究也报告称，在各种非视觉任务中，通常与视觉处理相关的枕叶内侧区域会被激活，但其对注意力转移的反应仍知之甚少。在这里，我们使用事件相关功能磁共振成像（fMRI）来探索CB个体和闭眼的有视力对照者（SC）的FEF和枕叶内侧区域，他们执行一项带有内源性语言提示和空间化听觉目标的隐蔽注意力定向任务。我们发现所有CB受试者都有强烈的刺激锁定FEF激活，与SC相似且更强，这表明即使在自愿眼球运动无关紧要的个体中，FEF在隐蔽空间注意力的内源性定向中也发挥作用。我们还发现CB受试者双侧枕叶内侧皮质有强烈激活，而SC受试者没有。在内源性语言提示后反应降至基线以下，但在听觉目标后增加，这表明CB个体的枕叶内侧区域在注意力的提示定向过程中不直接参与，但可能被用于处理空间化听觉目标。
