title: Dissociations and Associations between Shape and Category Representations in the Two Visual Pathways.
abstract: The dorsal and ventral visual pathways represent both visual and conceptual object properties. Yet the relative contribution of these two factors in the representational content of visual areas is unclear. Indeed, research investigating brain category representations rarely dissociate visual and semantic properties of objects. We present a human event-related fMRI study with a two-factorial stimulus set with 54 images that explicitly dissociates shape from category to investigate their independent contribution as well as their interactions through representational similarity analyses. Results reveal a contribution from each dimension in both streams, with a transition from shape to category along the posterior-to-anterior anatomical axis. The nature of category representations differs in the two pathways: ventral areas represent object animacy and dorsal areas represent object action properties. Furthermore, information about shape evolved from low-level pixel-based to high-level perceived shape following a posterior-to-anterior gradient similar to the shape-to-category emergence. To conclude, results show that representations of shape and category independently coexist, but at the same time they are closely related throughout the visual hierarchy.
  
  
  CONCLUSIONS
  Research investigating visual cortex conceptual category representations rarely takes into account visual properties of objects. In this report, we explicitly dissociate shape from category and investigate independent contributions and interactions of these two highly correlated dimensions.
authors.affiliation: Laboratory of Biological Psychology, KU Leuven, 3000, Belgium stefania.bracci@kuleuven.be.
authors.forename: Stefania
authors.identifier: http://orcid.org/0000-0003-1435-2536
authors.initials: S
authors.lastname: Bracci
authors.affiliation: Laboratory of Biological Psychology, KU Leuven, 3000, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Op de Beeck
mesh_terms: D000328:Adult; D001931:Brain Mapping; D016000:Cluster Analysis; D003210:Concept Formation / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007600:Judgment; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011601:Psychophysics; D014793:Visual Cortex / Q000098:blood supply / Q000502:physiology*; D014795:Visual Pathways / Q000098:blood supply / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: cortical organization; object category; object shape; representational similarity analysis; visual cortex