title: Neural representation of object orientation: A dissociation between MVPA and Repetition Suppression.
abstract: How is object orientation represented in the brain? Behavioral error patterns reveal systematic tendencies to confuse certain orientations with one another. Using fMRI, we asked whether more confusable orientations are represented more similarly in object selective cortex (LOC). We compared two widely-used measures of neural similarity: multi-voxel pattern similarity (MVP-similarity) and Repetition Suppression. In LO, we found that multi-voxel pattern similarity was predicted by the confusability of two orientations. By contrast, Repetition Suppression effects in LO were unrelated to the confusability of orientations. To account for these differences between MVP-similarity and Repetition Suppression, we propose that MVP-similarity reflects the topographical distribution of neural populations, whereas Repetition Suppression depends on repeated activation of particular groups of neurons. This hypothesis leads to a unified interpretation of our results and may explain other dissociations between MVPA and Repetition Suppression observed in the literature.
authors.affiliation: Department of Cognitive Science, Johns Hopkins University, Baltimore MD 21218, USA.
authors.forename: Miles
authors.initials: M
authors.lastname: Hatfield
authors.affiliation: Department of Cognitive Science, Johns Hopkins University, Baltimore MD 21218, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: McCloskey
authors.affiliation: Department of Cognitive Science, Johns Hopkins University, Baltimore MD 21218, USA. Electronic address: park@cogsci.jhu.edu.
authors.forename: Soojin
authors.initials: S
authors.lastname: Park
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D060865:Repetition Priming / Q000502:physiology*; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: Lateral occipital complex; Multi-voxel pattern analysis; Object orientation; Repetition Suppression; Representational similarity