title: Event-related potentials in response to emotional words in patients with major depressive disorder and healthy controls.
abstract: BACKGROUND
  Dysfunctional cognitive processing and abnormal brain activation in response to emotional stimuli have long been recognized as core features of the major depressive disorder (MDD). The aim of this study was to examine how Chinese patients with MDD process Chinese emotional words presented to either the left (LH) or right hemisphere (RH).
  
  
  METHODS
  Reaction time (RT) and the late positive component of the event-related potential were measured while subjects judged the valence (positive or negative) of emotional words written in Chinese.
  
  
  RESULTS
  Compared to healthy controls, patients with MDD exhibited slower RTs in response to negative words. In all subjects, the RTs in response to negative words were significantly faster than RTs in response to positive words presented to the LH, as well as significantly faster than responses to negative words presented to the RH. Compared to healthy controls, MDD patients exhibited reduced activation of the central and left regions of the brain in response to both negative and positive words. In healthy controls, the posterior brain areas were more active than the anterior brain areas when responding to negative words.
  
  
  CONCLUSIONS
  All individuals showed faster RTs in response to negative words compared to positive words. In addition, MDD patients showed lateralization of brain activity in response to emotional words, whereas healthy individuals did not show this lateralization. Posterior brain areas appear to play an especially important role in discriminating and experiencing negative emotional words. This study provides further evidence in support of the negative bias hypothesis and the emotional processing theory.
authors.affiliation: Medical Psychological Institute, Second Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Hui-fang
authors.initials: HF
authors.lastname: Yin
authors.forename: Da-xing
authors.initials: DX
authors.lastname: Wu
authors.forename: Shu-jing
authors.initials: SJ
authors.lastname: Xu
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D044466:Asian People; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000503:physiopathology* / Q000523:psychology*; D004569:Electroencephalography; D004644:Emotions / Q000502:physiology*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology*; D013997:Time Factors; D014825:Vocabulary; D055815:Young Adult