Automatic mood-congruent amygdala responses to masked facial expressions in major depression.
BACKGROUND
Cognitive theories of depression predict mood-congruent negative biases already at automatic stages of processing, although several behavioral studies seem to contradict this notion. That is, depression should potentiate emotional reactivity to negative emotional cues, whereas it should reduce reactivity in response to positive emotional stimuli. Assessing neurobiological substrates of automatic emotion processing might be a more sensitive challenge for automatic negative bias in depression than behavioral measures.


METHODS
In 30 acutely depressed inpatients and 26 healthy control subjects, automatic amygdala responses to happy and sad facial expressions were assessed by means of functional magnetic resonance imaging (fMRI) at 3 Tesla. To examine automatic responses, a presentation paradigm using subliminal, backward-masked stimuli was employed. A detection task was administered to assess participants' awareness of the masked emotional faces presented in the fMRI experiment.


RESULTS
Detection performance was at chance level for both patients and healthy control subjects, suggesting that the neurobiological reactions took place in absence of conscious awareness of the emotional stimuli. A robust emotion by group interaction was observed in the right amygdala. Whereas healthy control subjects demonstrated stronger responses to happy faces, depressed patients showed the opposite. Furthermore, amygdala responsiveness to happy facial expression was negatively correlated with current depression severity.


CONCLUSIONS
Depressed patients exhibit potentiated amygdala reactivity to masked negative stimuli along with a reduced responsiveness to masked positive stimuli compared with healthy individuals. Thus, depression is characterized by mood-congruent processing of emotional stimuli in the amygdala already at an automatic level of processing.
Suslow
Thomas
T
Department of Psychiatry, University of Münster, 48149 Münster, Germany. suslow@uni-muenster.de
Konrad
Carsten
C
Kugel
Harald
H
Rumstadt
Daniel
D
Zwitserlood
Pienie
P
Schöning
Sonja
S
Ohrmann
Patricia
P
Bauer
Jochen
J
Pyka
Martin
M
Kersting
Anette
A
Arolt
Volker
V
Heindel
Walter
W
Dannlowski
Udo
U
D000328:Adult; D000679:Amygdala / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D003865:Major Depressive Disorder / Q000503:physiopathology*; D004192:Discrimination, Psychological / Q000502:physiology; D004644:Emotions / Q000502:physiology*; D005149:Facial Expression; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D010364:Pattern Recognition, Visual / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D055815:Young Adult
D010100:Oxygen