title: Gaze-dependent topography in human posterior parietal cortex.
abstract: The brain must convert retinal coordinates into those required for directing an effector. One prominent theory holds that, through a combination of visual and motor/proprioceptive information, head-/body-centered representations are computed within the posterior parietal cortex (PPC). An alternative theory, supported by recent visual and saccade functional magnetic resonance imaging (fMRI) topographic mapping studies, suggests that PPC neurons provide a retinal/eye-centered coordinate system, in which the coding of a visual stimulus location and/or intended saccade endpoints should remain unaffected by changes in gaze position. To distinguish between a retinal/eye-centered and a head-/body-centered coordinate system, we measured how gaze direction affected the representation of visual space in the parietal cortex using fMRI. Subjects performed memory-guided saccades from a central starting point to locations "around the clock." Starting points varied between left, central, and right gaze relative to the head-/body midline. We found that memory-guided saccadotopic maps throughout the PPC showed spatial reorganization with very subtle changes in starting gaze position, despite constant retinal input and eye movement metrics. Such a systematic shift is inconsistent with models arguing for a retinal/eye-centered coordinate system in the PPC, but it is consistent with head-/body-centered coordinate representations.
authors.affiliation: Faculty of Medical Sciences, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK Current address: Wolfson Research Institute, University of Durham, Thornaby TS17 6BH, UK Current address: Department of Psychology, Durham University Science Site, Durham DH1 3LE, UK.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Connolly
authors.affiliation: Faculty of Medical Sciences, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Quoc C
authors.initials: QC
authors.lastname: Vuong
authors.affiliation: Faculty of Medical Sciences, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Thiele
mesh_terms: D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D005403:Fixation, Ocular / Q000502:physiology*; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010296:Parietal Lobe / Q000098:blood supply / Q000502:physiology*; D010775:Photic Stimulation; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways / Q000098:blood supply / Q000502:physiology*
chemical_list: D010100:Oxygen
keywords: functional magnetic resonance imaging; head-centered; posterior parietal cortex; spatial coordinate frames; topographic mapping