Espace et Action - Inserm 864, Université Claude Bernard, Lyon, France.
Cortex. 2010 Oct;46(9):1132-7. doi: 10.1016/j.cortex.2009.06.014. Epub 2009 Jul 15.
The pre-motor theory of attention suggests that the mechanisms involved in target selection for eye movements are the same as those for spatial attention shifts. The pre-saccadic facilitation of perceptual discrimination at the location of a saccadic goal (paradigm of Deubel and Schneider, 1996) has been considered as an argument for this theory. We compared letter discrimination performance in a saccade (overt attention - pre-saccadic facilitation) and a fixation (covert attention) task in a patient with right posterior parietal damage and 4 controls. In the overt attention condition, the patient was instructed by a central cue to make a saccade to a target located at a peripheral location. During the saccade latency (in a period of time of 250 msec following the presentation of the cue), a letter was presented at the target location. Accuracy of leftward saccades was impaired compared to rightward saccades. To evaluate letter discrimination performance in this saccade task (i.e., the presence of pre-saccadic facilitation), we selected only those leftward saccades that were equivalent in accuracy (and latency) to the rightward ones. Within these selected trials, the patient was able to discriminate letters equally well in both visual fields. In contrast, he performed at chance level during the fixation task (covert attention condition) for letters presented at the same peripheral location with the same timing with respect to the cue presentation. The patient could thus discriminate the letter presented at 8° of visual eccentricity while he was preparing a saccade, whereas he was unable to perceive the letter in the fixation task. Remarkably, in the left visual field, letter discrimination was impossible even when a letter was presented as close as 2.5° of visual eccentricity in the fixation task. Altogether, these results suggest that pre-saccadic perceptual facilitation does not rely on the same processes as those of covert attention, as tested by fixation task. Instead, we propose that pre-saccadic perceptual facilitation results from a form of attention specific to action, which could correspond to a pre-saccadic remapping process.
注意的前运动理论表明，参与眼球运动目标选择的机制与参与空间注意转移的机制相同。在扫视目标位置上知觉辨别力的前眼跳促进（Deubel 和 Schneider，1996 年的范式）被认为是这一理论的论据。我们比较了一名右后顶叶损伤患者和 4 名对照者在扫视（显性注意-前眼跳促进）和注视（隐性注意）任务中的字母辨别性能。在显性注意条件下，患者被中央提示指令进行扫视，将目光投向位于外周位置的目标。在扫视潜伏期（在提示呈现后 250 毫秒的一段时间内），目标位置呈现一个字母。与右眼扫视相比，左眼扫视的准确性受损。为了评估这个扫视任务中的字母辨别性能（即前眼跳促进的存在），我们只选择那些与右眼扫视准确性（和潜伏期）相等的左眼扫视。在这些选择的试验中，患者能够在两个视野中同样地辨别字母。相比之下，在注视任务（隐性注意条件）中，当字母在与提示呈现相同的外周位置以相同的时间呈现时，他的表现仅为随机水平。因此，患者在准备扫视时可以辨别出在 8°视离的字母，而在注视任务中他无法感知字母。值得注意的是，即使在注视任务中字母出现在距离仅 2.5°的视离内，患者在左视野中也无法进行字母辨别。总之，这些结果表明，前眼跳知觉促进并不依赖于作为注视任务测试的隐性注意的相同过程。相反，我们提出前眼跳知觉促进是一种特定于动作的注意力形式的结果，它可能对应于前眼跳重映射过程。
