title: Dissociation between dorsal and ventral posterior parietal cortical responses to incidental changes in natural scenes.
abstract: BACKGROUND
  The posterior parietal cortex (PPC) is thought to interact with the medial temporal lobe (MTL) to support spatial cognition and topographical memory. While the response of medial temporal lobe regions to topographical stimuli has been intensively studied, much less research has focused on the role of PPC and its functional connectivity with the medial temporal lobe.
  
  
  RESULTS
  Here we report a dissociation between dorsal and ventral regions of PPC in response to different types of change in natural scenes using an fMRI adaptation paradigm. During scanning subjects performed an incidental target detection task whilst viewing trial unique sequentially presented pairs of natural scenes, each containing a single prominent object. We observed a dissociation between the superior parietal gyrus and the angular gyrus, with the former showing greater sensitivity to spatial change, and the latter showing greater sensitivity to scene novelty. In addition, we observed that the parahippocampal cortex has increased functional connectivity with the angular gyrus, but not superior parietal gyrus, when subjects view change to the scene content.
  
  
  CONCLUSIONS
  Our findings provide support for proposed dissociations between dorsal and ventral regions of PPC and suggest that the dorsal PPC may support the spatial coding of the visual environment even when this information is incidental to the task at hand. Further, through revealing the differential functional interactions of the SPG and AG with the MTL our results help advance our understanding of how the MTL and PPC cooperate to update representations of the world around us.
authors.affiliation: Institute of Behavioural Neuroscience, Research Department of Cognitive, Perceptual and Brain Sciences, Division of Psychology and Language Sciences, University College London, London, United Kingdom.
authors.forename: Lorelei R
authors.initials: LR
authors.lastname: Howard
authors.forename: Dharshan
authors.initials: D
authors.lastname: Kumaran
authors.forename: H Freyja
authors.initials: HF
authors.lastname: Ólafsdóttir
authors.forename: Hugo J
authors.initials: HJ
authors.lastname: Spiers
mesh_terms: D001931:Brain Mapping; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation; D013028:Space Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology