title: Line quadrisection errors in patients with hemispatial neglect.
abstract: Patients with left unilateral neglect misbisect lines toward the right. To discriminate between contralesional unawareness and ipsilesional hyperattention hypotheses for this ipsilesional bias, we performed the line quadrisection test on 18 patients with and 25 without neglect, and 24 normal controls. Overall the patients with neglect were unbiased when performing the left quadrisection task, but erred rightward on the right quadrisection task. These results suggest that the ipsilesional bisection errors produced by patients with neglect are primarily influenced by ipsilesional hyperattention rather than contralesional unawareness. However, further analyses showed heterogeneity of performance in left quadrisection, which can be explained by multiple factors that include the top down attention to left space associated with left quadrisection, the orienting to the salience of the line's left end, and distorted mental representation, in addition to ipsilesional hyperattention.
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Byung Hwa
authors.initials: BH
authors.lastname: Lee
authors.forename: Sun U
authors.initials: SU
authors.lastname: Kwon
authors.forename: Jay C
authors.initials: JC
authors.lastname: Kwon
authors.forename: Min Jae
authors.initials: MJ
authors.lastname: Baek
authors.forename: Kwang Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Geon Ha
authors.initials: GH
authors.lastname: Kim
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Heilman
authors.forename: Duk L
authors.initials: DL
authors.lastname: Na
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010468:Perceptual Disorders / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*