Line bisection task performance and resting EEG alpha power.

Neurologically normal subjects generally err to the left of veridical center when performing a line bisection task, a phenomenon termed "pseudoneglect." We hypothesized that resting electroencephalogram (EEG) alpha oscillations may show relationships with attentional mechanisms and give some clues about the underlying mechanisms of pseudoneglect. We recorded resting EEGs of 41 subjects and tested them with a paper-pencil line bisection task. Our results showed that line bisection scores of men (n=18) were less biased and their performance was higher compared to those of women (n=20), but these differences only approached significance. The eyes open resting EEG alpha power of women was significantly and positively correlated with their line bisection performance. In general, significant relationships were related to the left hand performance when the lines were presented in the left hemispace. Greater resting alpha power was correlated with lower absolute bisection score or, in other words, higher bisection performance. Greater alpha power also correlated with diminished leftward bisection bias (or reduced pseudo-neglect). The resting EEG alpha of men was weakly associated with bisection performance. Results discussed in terms of Kinsbourne's activation-orientation theory and Basar's view on brain oscillations.