title: Far-space neglect in conjunction but not feature search following transcranial magnetic stimulation over right posterior parietal cortex.
abstract: Near- and far-space coding in the human brain is a dynamic process. Areas in dorsal, as well as ventral visual association cortex, including right posterior parietal cortex (rPPC), right frontal eye field (rFEF), and right ventral occipital cortex (rVO), have been shown to be important in visuospatial processing, but the involvement of these areas when the information is in near or far space remains unclear. There is a need for investigations of these representations to help explain the pathophysiology of hemispatial neglect, and the role of near and far space is crucial to this. We used a conjunction visual search task using an elliptical array to investigate the effects of transcranial magnetic stimulation delivered over rFEF, rPPC, and rVO on the processing of targets in near and far space and at a range of horizontal eccentricities. As in previous studies, we found that rVO was involved in far-space search, and rFEF was involved regardless of the distance to the array. It was found that rPPC was involved in search only in far space, with a neglect-like effect when the target was located in the most eccentric locations. No effects were seen for any site for a feature search task. As the search arrays had higher predictability with respect to target location than is often the case, these data may form a basis for clarifying both the role of PPC in visual search and its contribution to neglect, as well as the importance of near and far space in these.
authors.affiliation: Institute of Cognitive Neuroscience, National Central University, Jhongli, Taiwan;
authors.forename: Indra T
authors.initials: IT
authors.lastname: Mahayana
authors.forename: Chia-Lun
authors.initials: CL
authors.lastname: Liu
authors.forename: Chi Fu
authors.initials: CF
authors.lastname: Chang
authors.forename: Daisy L
authors.initials: DL
authors.lastname: Hung
authors.forename: Ovid J L
authors.initials: OJ
authors.lastname: Tzeng
authors.forename: Chi-Hung
authors.initials: CH
authors.lastname: Juan
authors.forename: Neil G
authors.initials: NG
authors.lastname: Muggleton
mesh_terms: D000328:Adult; D005133:Eye Movements; D005260:Female; D006801:Humans; D008297:Male; D009778:Occipital Lobe / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D013028:Space Perception; D050781:Transcranial Magnetic Stimulation
keywords: far space; near space; parietal cortex; visual search