title: Tripartite organization of the ventral stream by animacy and object size.
abstract: Occipito-temporal cortex is known to house visual object representations, but the organization of the neural activation patterns along this cortex is still being discovered. Here we found a systematic, large-scale structure in the neural responses related to the interaction between two major cognitive dimensions of object representation: animacy and real-world size. Neural responses were measured with functional magnetic resonance imaging while human observers viewed images of big and small animals and big and small objects. We found that real-world size drives differential responses only in the object domain, not the animate domain, yielding a tripartite distinction in the space of object representation. Specifically, cortical zones with distinct response preferences for big objects, all animals, and small objects, are arranged in a spoked organization around the occipital pole, along a single ventromedial, to lateral, to dorsomedial axis. The preference zones are duplicated on the ventral and lateral surface of the brain. Such a duplication indicates that a yet unknown higher-order division of labor separates object processing into two substreams of the ventral visual pathway. Broadly, we suggest that these large-scale neural divisions reflect the major joints in the representational structure of objects and thus place informative constraints on the nature of the underlying cognitive architecture.
authors.affiliation: Center for Mind/Brain Sciences, University of Trento, 38068 Rovereto (TN), Italy. onkle@fas.harvard.edu
authors.forename: Talia
authors.initials: T
authors.lastname: Konkle
authors.forename: Alfonso
authors.initials: A
authors.lastname: Caramazza
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D019540:Area Under Curve; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D003071:Cognition / Q000502:physiology; D005145:Face; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008606:Mental Processes / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D010775:Photic Stimulation; D012858:Size Perception / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult