title: Selective modulations of attentional asymmetries after sleep deprivation.
abstract: 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.
authors.affiliation: UR2NF [Unité de Recherches en Neuropsychologie et Neuroimagerie Fonctionnelle], Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Rémy
authors.initials: R
authors.lastname: Schmitz
authors.forename: Gaétane
authors.initials: G
authors.lastname: Deliens
authors.forename: Alison
authors.initials: A
authors.lastname: Mary
authors.forename: Charline
authors.initials: C
authors.lastname: Urbain
authors.forename: Philippe
authors.initials: P
authors.lastname: Peigneux
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001143:Arousal / Q000502:physiology; D001289:Attention Deficit Disorder with Hyperactivity / Q000209:etiology*; D015982:Bias; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011597:Psychomotor Performance; D011930:Reaction Time; D012892:Sleep Deprivation / Q000150:complications*; D013028:Space Perception / Q000502:physiology*; D013223:Statistics as Topic; D013997:Time Factors; D055815:Young Adult