title: The precuneus and visuospatial attention in near and far space: a transcranial magnetic stimulation study.
abstract: BACKGROUND
  There is a large body of evidence for the involvement of the parietal cortex in orientation and navigation in space. This has been supplemented by investigation of the contribution of a number of subregions using transcranial magnetic stimulation.
  
  
  OBJECTIVE
  The role of the precuneus area, located in the medial plane of posterior parietal cortex (PPC), in visuospatial functions is not well understood. We investigated the contribution of this area using the landmark task.
  
  
  METHODS
  Participants were asked to make forced-choice judgments of which side of prebisected line was longer for near and far viewing conditions (70 and 180 cm, respectively). Online 10 Hz, repetitive transcranial magnetic stimulation (rTMS) was delivered for 500 ms over the right precuneus, rPPC and vertex (control), in separate blocks of trials. The rPPC stimulation was used as a positive control, having previously resulted in "neglect like" spatial bias effects in a number of studies.
  
  
  RESULTS
  A no-TMS condition showed a leftward spatial bias (pseudoneglect) for near space judgments but not for far space and was used as the baseline. Precuneus stimulation resulted in rightward spatial bias from the midpoint in near space similar to the rPPC neglect-like effect. No significant effects were seen with vertex stimulation.
  
  
  CONCLUSIONS
  This study shows that precuneus, like other parietal areas, is involved in visuospatial functions. Further work is required to clarify how the contribution of this area differs from other parietal regions.
authors.affiliation: Institute of Cognitive Neuroscience, National Central University, Jhongli 320, Taiwan.
authors.forename: Indra T
authors.initials: IT
authors.lastname: Mahayana
authors.affiliation: Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, UK.
authors.forename: Lili
authors.initials: L
authors.lastname: Tcheang
authors.affiliation: Department and Graduate Institute of Criminology, National Chung Cheng University, Chiayi, Taiwan.
authors.forename: Chiao-Yun
authors.initials: CY
authors.lastname: Chen
authors.affiliation: Institute of Cognitive Neuroscience, National Central University, Jhongli 320, Taiwan.
authors.forename: Chi-Hung
authors.initials: CH
authors.lastname: Juan
authors.affiliation: Institute of Cognitive Neuroscience, National Central University, Jhongli 320, Taiwan; Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, UK; Department of Psychology, Goldsmiths, University of London, New Cross, London, UK. Electronic address: neil.muggleton@gmail.com.
authors.forename: Neil G
authors.initials: NG
authors.lastname: Muggleton
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D002755:Choice Behavior / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009949:Orientation / Q000502:physiology; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: Landmark task; Neglect-like effect; Parietal cortex; Precuneus; TMS; Visuospatial attention