title: Fine-grained stimulus representations in body selective areas of human occipito-temporal cortex.
abstract: Neurophysiological and functional imaging studies have investigated the representation of animate and inanimate stimulus classes in monkey inferior temporal (IT) and human occipito-temporal cortex (OTC). These studies proposed a distributed representation of stimulus categories across IT and OTC and at the same time highlighted category specific modules for the processing of bodies, faces and objects. Here, we investigated whether the stimulus representation within the extrastriate (EBA) and the fusiform (FBA) body areas differed from the representation across OTC. To address this question, we performed an event-related fMRI experiment, evaluating the pattern of activation elicited by 200 individual stimuli that had already been extensively tested in our earlier monkey imaging and single cell studies (Popivanov et al., 2012, 2014). The set contained achromatic images of headless monkey and human bodies, two sets of man-made objects, monkey and human faces, four-legged mammals, birds, fruits, and sculptures. The fMRI response patterns within EBA and FBA primarily distinguished bodies from non-body stimuli, with subtle differences between the areas. However, despite responding on average stronger to bodies than to other categories, classification performance for preferred and non-preferred categories was comparable. OTC primarily distinguished animate from inanimate stimuli. However, cluster analysis revealed a much more fine-grained representation with several homogeneous clusters consisting entirely of stimuli of individual categories. Overall, our data suggest that category representation varies with location within OTC. Nevertheless, body modules contain information to discriminate also non-preferred stimuli and show an increasing specificity in a posterior to anterior gradient.
authors.affiliation: Laboratorium voor Neuro-en Psychofysiologie, KU Leuven, Leuven, Belgium.
authors.forename: Natalie
authors.initials: N
authors.lastname: Caspari
authors.affiliation: Laboratorium voor Neuro-en Psychofysiologie, KU Leuven, Leuven, Belgium.
authors.forename: Ivo D
authors.initials: ID
authors.lastname: Popivanov
authors.affiliation: Department of Healthcare & Technology, KH Leuven, Leuven, Belgium; Department of Computer Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Patrick A
authors.initials: PA
authors.lastname: De Mazière
authors.affiliation: Laboratorium voor Neuro-en Psychofysiologie, KU Leuven, Leuven, Belgium; Harvard Med. Sch., Boston, MA, USA; MGH Martinos Ctr., Charlestown, MA, USA.
authors.forename: Wim
authors.initials: W
authors.lastname: Vanduffel
authors.affiliation: Laboratorium voor Neuro-en Psychofysiologie, KU Leuven, Leuven, Belgium.
authors.forename: Rufin
authors.initials: R
authors.lastname: Vogels
authors.affiliation: Department of Neuroscience, University of Parma, Parma, Italy.
authors.forename: Guy A
authors.initials: GA
authors.lastname: Orban
authors.affiliation: Laboratorium voor Neuro-en Psychofysiologie, KU Leuven, Leuven, Belgium; Division of Psychiatry, Department of Neuroscience, KU Leuven, Leuven, Belgium. Electronic address: jan.jastorff@med.kuleuven.be.
authors.forename: Jan
authors.initials: J
authors.lastname: Jastorff
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005074:Evoked Potentials, Visual; D005145:Face; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009778:Occipital Lobe / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D013702:Temporal Lobe / Q000502:physiology*; D060726:Torso; D055815:Young Adult
keywords: Bodies; Extrastriate body area; Functional imaging; Fusiform body area; Human; Monkey; Multi-voxel pattern analysis