title: Vestibular information is necessary for maintaining metric properties of representational space: evidence from mental imagery.
abstract: The vestibular system contributes to a wide range of functions, from postural and oculomotor reflexes to spatial representation and cognition. Vestibular signals are important to maintain an internal, updated representation of the body position and movement in space. However, it is not clear to what extent they are also necessary to mentally simulate movement in situations that do not involve displacements of the body, as in mental imagery. The present study assessed how vestibular loss can affect object-based mental transformations (OMTs), i.e., imagined rotations or translations of objects relative to the environment. Participants performed one task of mental rotation of 3D-objects and two mental scanning tasks dealing with the ability to build and manipulate mental images that have metric properties. Menière's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (1 week and 1 month). They were compared to healthy participants tested at similar time intervals and to bilateral vestibular-defective patients tested after the recovery period. Vestibular loss impaired all mental imagery tasks. Performance varied according to the extent of vestibular loss (bilateral patients were frequently the most impaired) and according to the time elapsed after unilateral vestibular neurotomy (deficits were stronger at the early stage after neurotomy and then gradually compensated). These findings indicate that vestibular signals are necessary to perform OMTs and provide the first demonstration of the critical role of vestibular signals in processing metric properties of mental representations. They suggest that vestibular loss disorganizes brain structures commonly involved in mental imagery, and more generally in mental representation.
authors.affiliation: INSERM U751 Epilepsie & Cognition, Université de la Méditerranée, Faculté de Médecine de la Timone, Marseille, France. patrick.peruch@univmed.fr
authors.forename: Patrick
authors.initials: P
authors.lastname: Péruch
authors.forename: Christophe
authors.initials: C
authors.lastname: Lopez
authors.forename: Christine
authors.initials: C
authors.lastname: Redon-Zouiteni
authors.forename: Guy
authors.initials: G
authors.lastname: Escoffier
authors.forename: Alain
authors.initials: A
authors.lastname: Zeitoun
authors.forename: Mélanie
authors.initials: M
authors.lastname: Sanjuan
authors.forename: Arnaud
authors.initials: A
authors.lastname: Devèze
authors.forename: Jacques
authors.initials: J
authors.lastname: Magnan
authors.forename: Liliane
authors.initials: L
authors.lastname: Borel
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008297:Male; D008575:Meniere Disease / Q000503:physiopathology; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology; D012399:Rotation; D013028:Space Perception / Q000502:physiology*; D015837:Vestibular Diseases / Q000503:physiopathology; D014722:Vestibule, Labyrinth / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology