title: Similar or different? The role of the ventrolateral prefrontal cortex in similarity detection.
abstract: Patients with frontal lobe syndrome can exhibit two types of abnormal behaviour when asked to place a banana and an orange in a single category: some patients categorize them at a concrete level (e.g., "both have peel"), while others continue to look for differences between these objects (e.g., "one is yellow, the other is orange"). These observations raise the question of whether abstraction and similarity detection are distinct processes involved in abstract categorization, and that depend on separate areas of the prefrontal cortex (PFC). We designed an original experimental paradigm for a functional magnetic resonance imaging (fMRI) study involving healthy subjects, confirming the existence of two distinct processes relying on different prefrontal areas, and thus explaining the behavioural dissociation in frontal lesion patients. We showed that: 1) Similarity detection involves the anterior ventrolateral PFC bilaterally with a right-left asymmetry: the right anterior ventrolateral PFC is only engaged in detecting physical similarities; 2) Abstraction per se activates the left dorsolateral PFC.
authors.affiliation: CR-ICM-UPMC, Inserm UMR_S 975;CNRS UMR 7225, Groupe Hospitalier Pitié-Salpêtrière, Paris, France. beagarcin@msn.com
authors.forename: Béatrice
authors.initials: B
authors.lastname: Garcin
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Volle
authors.forename: Bruno
authors.initials: B
authors.lastname: Dubois
authors.forename: Richard
authors.initials: R
authors.lastname: Levy
mesh_terms: D000328:Adult; D001288:Attention; D001519:Behavior; D001931:Brain Mapping / Q000379:methods; D003071:Cognition; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D017397:Prefrontal Cortex / Q000502:physiology*; D015203:Reproducibility of Results; D014741:Video Recording