title: Abnormal self-schema in semantic memory in major depressive disorder: Evidence from event-related brain potentials.
abstract: An overly negative self-schema is a proposed cognitive mechanism of major depressive disorder (MDD). Self-schema - one's core conception of self, including how strongly one believes one possesses various characteristics - is part of semantic memory (SM), our knowledge about concepts and their relationships. We used the N400 event-related potential (ERP) - elicited by meaningful stimuli, and reduced by greater association of the stimulus with preceding context - to measure association strength between self-concept and positive, negative, and neutral characteristics in SM. ERPs were recorded from MDD patients (n=16) and controls (n=16) who viewed trials comprising a self-referential phrase followed by a positive, negative, or neutral adjective. Participants' task was to indicate via button-press whether or not they felt each adjective described themselves. Controls endorsed more positive adjectives than did MDD patients, but the opposite was true for negative adjectives. Patients had smaller N400s than controls specifically for negative adjectives, suggesting that MDD is associated with stronger than normal functional neural links between self-concept and negative characteristics in SM.
authors.affiliation: Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada. Electronic address: michael.kiang@camh.ca.
authors.forename: Michael
authors.initials: M
authors.lastname: Kiang
authors.affiliation: Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Faranak
authors.initials: F
authors.lastname: Farzan
authors.affiliation: Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Blumberger
authors.affiliation: Department of Cognitive Science and Department of Neurosciences, University of California (San Diego), La Jolla, CA, USA.
authors.forename: Marta
authors.initials: M
authors.lastname: Kutas
authors.affiliation: St. Joseph's Healthcare Hamilton, Hamilton, Ontario, Canada; Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Margaret C
authors.initials: MC
authors.lastname: McKinnon
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Vinay
authors.initials: V
authors.lastname: Kansal
authors.affiliation: Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Tarek K
authors.initials: TK
authors.lastname: Rajji
authors.affiliation: Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Zafiris J
authors.initials: ZJ
authors.lastname: Daskalakis
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000503:physiopathology; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000503:physiopathology / Q000523:psychology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D012649:Self Concept; D012660:Semantics; D055815:Young Adult
keywords: Electroencephalography; Event-related potentials; Language; Major depressive disorder; Self-schema; Semantic memory