UR2NF [Unité de Recherches en Neuropsychologie et Neuroimagerie Fonctionnelle], Université Libre de Bruxelles, Brussels, Belgium.
Neuropsychologia. 2011 Oct;49(12):3351-60. doi: 10.1016/j.neuropsychologia.2011.08.009. Epub 2011 Aug 17.
Pseudoneglect is a slight but consistent misplacement of attention toward the left visual field, commonly observed in young healthy subjects. This leftward attentional bias is thought to result from a right hemispheric dominance in visuospatial processing. Changes in endogenous levels of alertness may modulate attentional asymmetries and pseudoneglect in particular. In line with this hypothesis, it has been shown that sleep deprived shift-workers present a reversal of their attentional bias in a landmark (LDM) task (Manly, T., Dobler, V. B., Dodds, C. M., & George, M. A. (2005). Rightward shift in spatial awareness with declining alertness. Neuropsychologia, 43(12), 1721-1728). However, circadian disturbances and fatigue effects at the end of a shift work may have contributed to this reversal effect. In a first experiment, we show that sleep deprivation (SD) under controlled conditions does not markedly change the leftward bias, observable both at 21:00 and at 07:00 after SD. In a second experiment, we tested the hypothesis that a drastic reduction or inversion in the attentional bias would be present only when both the circadian drive for sleep propensity is maximal (i.e. around 05:00) and homeostatic sleep pressure is high. Thus participants were tested at 21:00 and under SD conditions at 05:00 and 09:00. Additionally, we used the greyscales (GS) task well-known to evidence a leftward bias in luminance judgments. Although results evidenced a consistent leftward bias both in the LDM and GS, we found a suppression of the leftward bias at the circadian nadir of alertness (05:00) after SD only for the GS, but not for the LDM. Noticeably, the leftward bias in the GS vanished at 05:00 after SD but reappeared at 09:00 despite continued SD, suggesting a predominant circadian influence on attentional asymmetries in the GS. Additionally, inter-sessions correlations evidenced a reproducible, consistent bias both in the LDM and GS, with no consistent relationship between the two tasks, suggesting independence of the neural networks subtending performance in LDM and GS. Overall, our results suggest that SD per se does not impede the leftward bias both in LDM and GS, whereas circadian-related variations in vigilance may impact attentional asymmetries in luminance judgments.
偏侧忽略是一种轻微但持续的注意力左偏，常见于年轻健康的受试者。这种左向注意力偏差被认为是由于右侧半球在视空间处理中的优势所致。内源性警觉水平的变化可能会调节注意力不对称，特别是偏侧忽略。根据这一假设，已经表明睡眠剥夺的轮班工人在地标（LDM）任务中表现出注意力偏差的逆转（Manly，T.，Dobler，VB，Dodds，CM，& George，MA.（2005）。警觉下降时，空间意识向右转移。神经心理学，43（12），1721-1728）。然而，轮班结束时的昼夜节律紊乱和疲劳效应可能促成了这种逆转效应。在第一个实验中，我们表明，在控制条件下的睡眠剥夺（SD）不会显著改变可观察到的左偏，无论是在 SD 后 21:00 还是 07:00。在第二个实验中，我们假设只有在睡眠倾向的昼夜节律驱动最大（即 05:00 左右）并且稳态睡眠压力高时，注意力偏差才会急剧减少或反转。因此，参与者在 21:00 进行测试，并在 05:00 和 09:00 在 SD 条件下进行测试。此外，我们使用灰度级（GS）任务来证明亮度判断中的左偏。尽管结果表明 LDM 和 GS 都存在一致的左偏，但我们发现只有在 GS 中，在 SD 后的警觉昼夜节律低谷（05:00）时，才会抑制左偏，而在 LDM 中则不会。值得注意的是，尽管继续进行 SD，但在 SD 后 05:00 时，GS 的左偏消失，但在 09:00 时又出现，这表明昼夜节律对 GS 中的注意力不对称有主要影响。此外，跨会话相关性表明，在 LDM 和 GS 中都存在可重复的、一致的偏差，并且两个任务之间没有一致的关系，这表明支撑 LDM 和 GS 表现的神经网络是独立的。总体而言，我们的结果表明，SD 本身不会妨碍 LDM 和 GS 中的左偏，而警觉性的昼夜节律变化可能会影响亮度判断中的注意力不对称。
