title: On the neural origin of pseudoneglect: EEG-correlates of shifts in line bisection performance with manipulation of line length.
abstract: Healthy participants tend to show systematic biases in spatial attention, usually to the left. However, these biases can shift rightward as a result of a number of experimental manipulations. Using electroencephalography (EEG) and a computerized line bisection task, here we investigated for the first time the neural correlates of changes in spatial attention bias induced by line-length (the so-called line-length effect). In accordance with previous studies, an overall systematic left bias (pseudoneglect) was present during long line but not during short line bisection performance. This effect of line-length on behavioral bias was associated with stronger right parieto-occipital responses to long as compared to short lines in an early time window (100-200ms) post-stimulus onset. This early differential activation to long as compared to short lines was task-independent (present even in a non-spatial control task not requiring line bisection), suggesting that it reflects a reflexive attentional response to long lines. This was corroborated by further analyses source-localizing the line-length effect to the right temporo-parietal junction (TPJ) and revealing a positive correlation between the strength of this effect and the magnitude by which long lines (relative to short lines) drive a behavioral left bias across individuals. Therefore, stimulus-driven left bisection bias was associated with increased right hemispheric engagement of areas of the ventral attention network. This further substantiates that this network plays a key role in the genesis of spatial bias, and suggests that post-stimulus TPJ-activity at early information processing stages (around the latency of the N1 component) contributes to the left bias.
authors.affiliation: Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QB, UK; School of Psychology, University of Glasgow, Glasgow G12 8QB, UK. Electronic address: chrisb@psy.gla.ac.uk.
authors.forename: Christopher S Y
authors.initials: CS
authors.lastname: Benwell
authors.affiliation: School of Psychology, University of Glasgow, Glasgow G12 8QB, UK.
authors.forename: Monika
authors.initials: M
authors.lastname: Harvey
authors.affiliation: Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow G12 8QB, UK.
authors.forename: Gregor
authors.initials: G
authors.lastname: Thut
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D003463:Cues; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods*; D013028:Space Perception / Q000502:physiology*; D055815:Young Adult
keywords: Attention; EEG; Event-related potentials; Landmark task; Pseudoneglect; Spatial bias