title: Increased neural activity during overt and continuous semantic verbal fluency in major depression: mainly a failure to deactivate.
abstract: Major depression is associated with impairments in semantic verbal fluency (VF). However, the neural correlates underlying dysfunctional cognitive processing in depressed subjects during the production of semantic category members still remain unclear. In the current study, an overt and continuous semantic VF paradigm was used to examine these mechanisms in a representative sample of 33 patients diagnosed with a current episode of unipolar depression and 33 statistically matched healthy controls. Subjects articulated words in response to semantic category cues while brain activity was measured with functional magnetic resonance imaging (fMRI). Compared to controls, patients showed poorer task performance. On the neural level, a group by condition interaction analysis, corrected for task performance, revealed a reduced task-related deactivation in patients in the right parahippocampal gyrus, the right fusiform gyrus, and the right supplementary motor area. An additional and an increased task-related activation in patients were observed in the right precentral gyrus and the left cerebellum, respectively. These results indicate that a failure to suppress potentially interfering activity from inferior temporal regions involved in default-mode network functions and visual imagery, accompanied by an enhanced recruitment of areas implicated in speech initiation and higher-order language processes, may underlie dysfunctional cognitive processing during semantic VF in depression. The finding that patients with depression demonstrated both decreased performance and aberrant brain activation during the current semantic VF task demonstrates that this paradigm is a sensitive tool for assessing brain dysfunctions in clinical populations.
authors.affiliation: Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039, Marburg, Germany, Heidelore.Backes@med.uni-marburg.de.
authors.forename: Heidelore
authors.initials: H
authors.lastname: Backes
authors.forename: Bruno
authors.initials: B
authors.lastname: Dietsche
authors.forename: Arne
authors.initials: A
authors.lastname: Nagels
authors.forename: Mirjam
authors.initials: M
authors.lastname: Stratmann
authors.forename: Carsten
authors.initials: C
authors.lastname: Konrad
authors.forename: Tilo
authors.initials: T
authors.lastname: Kircher
authors.forename: Axel
authors.initials: A
authors.lastname: Krug
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply / Q000473:pathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000150:complications*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007806:Language Disorders / Q000209:etiology* / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D012660:Semantics; D014705:Verbal Behavior; D055815:Young Adult
chemical_list: D010100:Oxygen