title: Establishing the boundaries: the hippocampal contribution to imagining scenes.
abstract: When we visualize scenes, either from our own past or invented, we impose a viewpoint for our "mind's eye" and we experience the resulting image as spatially coherent from that viewpoint. The hippocampus has been implicated in this process, but its precise contribution is unknown. We tested a specific hypothesis based on the spatial firing properties of neurons in the hippocampal formation of rats, that this region supports the construction of spatially coherent mental images by representing the locations of the environmental boundaries surrounding our viewpoint. Using functional magnetic resonance imaging, we show that hippocampal activation increases parametrically with the number of enclosing boundaries in the imagined scene. In contrast, hippocampal activity is not modulated by a nonspatial manipulation of scene complexity nor to increasing difficulty of imagining the scenes in general. Our findings identify a specific computational role for the hippocampus in mental imagery and episodic recollection.
authors.affiliation: UCL Institute of Cognitive Neuroscience and UCL Institute of Neurology, University College London, London, United Kingdom. chris.bird@ucl.ac.uk
authors.forename: Chris M
authors.initials: CM
authors.lastname: Bird
authors.forename: Corinne
authors.initials: C
authors.lastname: Capponi
authors.forename: John A
authors.initials: JA
authors.lastname: King
authors.forename: Christian F
authors.initials: CF
authors.lastname: Doeller
authors.forename: Neil
authors.initials: N
authors.lastname: Burgess
mesh_terms: D000328:Adult; D000818:Animals; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology; D011939:Mental Recall / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods*; D011597:Psychomotor Performance / Q000502:physiology; D051381:Rats; D013028:Space Perception / Q000502:physiology; D055815:Young Adult
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