General and Experimental Psychology/Neuro-Cognitive Psychology, Ludwig Maximilian University, Munich, Germany.
Neuropsychologia. 2012 May;50(6):1178-89. doi: 10.1016/j.neuropsychologia.2012.02.008. Epub 2012 Feb 23.
In visual hemi-neglect, non-spatial deficits such as reduced intrinsic alertness can significantly modulate the degree of left visual field inattention. However, to date, the precise mechanisms mediating this effect are hardly understood. In the present study, we assessed the influence of increased alertness on both general attentional capacity (perceptual processing speed) and spatial attentional selection processes (spatial distribution of attentional weighting). For this purpose, a whole-report paradigm based on Bundesen's 'theory of visual attention' (TVA) was combined with a non-spatial, visual alerting cue. Three different cue-target stimulus onset asynchronies (SOAs; of 80, 200, and 650 ms), allowed us to observe the time course of the alerting-cue effects. A group of six patients with visual hemi-neglect was examined and their performance compared with six healthy control subjects matched for age, gender, and education. In neglect patients, the alerting cue evoked a phasic increase of perceptual processing speed. However, this effect was mainly found in the ipsilateral, i.e. in the "preserved" hemifield. Importantly, however, patients displayed a fast-evolving and short-lasting, phasic modulation of spatial attentional weighting, with a re-distribution of attentional weights from the pathological rightward bias to a normal, more balanced distribution of visual attention. In control participants, the cueing effects on perceptual processing speed and spatial weighting were generally less pronounced than in neglect patients. Replicating results of a prior study, cueing induced a stable, slightly leftward, distribution of attentional weights, whilst in the no-cue condition, a temporary rightward shift of attentional weights was found. This pattern of effects suggests a close interaction between alertness and spatial-attentional weighting in the syndrome of visual hemi-neglect. It supports the hypothesis that the manifestation of spatial neglect involves at least in part intrinsic alertness deficits. It also provides clues to a more detailed account of the mechanisms responsible for alleviating neglect in patients following manipulations of the alertness level, both in the short (cueing) and in the long term (alertness training).
在单侧忽略中，非空间缺陷，如警觉性降低，会显著调节左视野注意缺陷的程度。然而，迄今为止，介导这种效应的精确机制几乎不为人知。在本研究中，我们评估了警觉性的增加对一般注意力容量（感知处理速度）和空间注意力选择过程（注意力权重的空间分布）的影响。为此，我们结合了非空间视觉警示线索，使用基于 Bundesen“视觉注意力理论”（TVA）的全报告范式。三个不同的提示-目标刺激起始时间间隔（SOA；80、200 和 650 毫秒），使我们能够观察到警示线索效应的时间进程。我们检查了一组 6 名单侧忽略患者，并将他们的表现与年龄、性别和教育程度相匹配的 6 名健康对照者进行了比较。在忽略患者中，警示线索引起了感知处理速度的阶段性增加。然而，这种效应主要出现在同侧，即“保留”的半视野中。重要的是，然而，患者表现出快速演变和短暂的、阶段性的空间注意力权重调制，注意力权重从病理性的右偏重新分布到正常的、更平衡的视觉注意力分布。在对照组参与者中，与忽略患者相比，线索对感知处理速度和空间权重的影响通常不那么明显。复制先前研究的结果，线索引起了注意力权重的稳定、略微左偏分布，而在无线索条件下，注意力权重会暂时向右移动。这种效应模式表明，在单侧忽略综合征中，警觉性和空间注意力权重之间存在密切的相互作用。它支持了这样一种假设，即空间忽略的表现至少部分涉及内在警觉性缺陷。它还为更详细地解释负责减轻患者忽略的机制提供了线索，这些机制既包括短期（线索），也包括长期（警觉性训练）。
