title: Hyperfrontality and hypoconnectivity during refreshing in schizophrenia.
abstract: Anomalous activations of the prefrontal cortex (PFC) and posterior cerebral areas have been reported in previous studies of working memory in schizophrenia. Several interpretations have been reported: e.g., neural inefficiency, the use of different strategies and differences in the functional organization of the cerebral cortex. To better understand these abnormal activations, we investigated the cerebral bases of a working memory component process, namely refreshing (i.e., thinking briefly of a just-activated representation). Fifteen patients with schizophrenia and 15 control subjects participated in this functional magnetic resonance imaging (fMRI) study. Participants were told that whenever they saw a word on the screen, they had to read it silently to themselves (read and repeat conditions), and when they saw a dot, they had to think of the just-previous word (refresh condition). The refresh condition (in comparison with the read condition) was associated with significantly increased activation in the left inferior frontal gyrus and significantly decreased connectivity within the prefrontal cortex and between the prefrontal and parietal cortices in patients with schizophrenia in comparison with control subjects. These results suggest that prefrontal dysfunctions in schizophrenia might be related to a defective ability to initiate (rather than to execute) specific cognitive processes.
authors.affiliation: Inserm U894, Université Paris Descartes, Centre de Psychiatrie et Neurosciences, Centre Hospitalier Sainte-Anne, Paris, France. mlgrillon@gmail.com
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Grillon
authors.forename: Catherine
authors.initials: C
authors.lastname: Oppenheim
authors.forename: Gaël
authors.initials: G
authors.lastname: Varoquaux
authors.forename: Frédérique
authors.initials: F
authors.lastname: Charbonneau
authors.forename: Anne-Dominique
authors.initials: AD
authors.lastname: Devauchelle
authors.forename: Marie-Odile
authors.initials: MO
authors.lastname: Krebs
authors.forename: Franck
authors.initials: F
authors.lastname: Baylé
authors.forename: Bertrand
authors.initials: B
authors.lastname: Thirion
authors.forename: Caroline
authors.initials: C
authors.lastname: Huron
mesh_terms: D000328:Adult; D001931:Brain Mapping; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000098:blood supply / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000209:etiology / Q000473:pathology; D008570:Memory, Short-Term / Q000502:physiology*; D009434:Neural Pathways / Q000098:blood supply / Q000503:physiopathology; D009483:Neuropsychological Tests; D010045:Outpatients; D010100:Oxygen; D012559:Schizophrenia / Q000150:complications / Q000473:pathology*; D014706:Verbal Learning / Q000502:physiology; D055815:Young Adult
chemical_list: D010100:Oxygen