title: Effects of acute tryptophan depletion on neural processing of facial expressions of emotion in humans.
abstract: BACKGROUND
  Acute tryptophan depletion (ATD) temporarily lowers brain serotonin (5-HT) synthesis, and behavioral studies have shown that this alters the processing of facial expressions of emotion.
  
  
  METHODS
  The neural basis for these alterations is not known. Therefore, we employed ATD and event-related functional magnetic resonance imaging (fMRI) to examine neural responses during incidental processing of fearful, happy, sad, and disgusted facial expressions. Fourteen healthy male controls (age, 28 +/- 10) were scanned under both placebo (SHAM) and depletion (ATD) conditions.
  
  
  CONCLUSIONS
  We predicted that ATD would be associated with changes in neural activity within facial emotion-processing networks. We found that serotonergic modulation did not affect performance on the fMRI tasks, but was associated with widespread effects on neural response to components of face processing networks for fearful, disgusted, and happy but not sad expressions across differing intensities.
  
  
  CONCLUSIONS
  Hence, the 5-HT system affects brain function (in 'limbic' and 'face processing' regions) during incidental processing of emotional facial expressions; but this varies with emotion type and intensities.
authors.affiliation: Section of Brain Maturation, Department of Psychological Medicine and Psychiatry, Institute of Psychiatry, King's College London, London, UK. eileen.m.daly@kcl.ac.uk
authors.forename: Eileen
authors.initials: E
authors.lastname: Daly
authors.forename: Quinton
authors.initials: Q
authors.lastname: Deeley
authors.forename: Brian
authors.initials: B
authors.lastname: Hallahan
authors.forename: Michael
authors.initials: M
authors.lastname: Craig
authors.forename: Michael
authors.initials: M
authors.lastname: Brammer
authors.forename: Melissa
authors.initials: M
authors.lastname: Lamar
authors.forename: Anthony
authors.initials: A
authors.lastname: Cleare
authors.forename: Vincent
authors.initials: V
authors.lastname: Giampietro
authors.forename: Christine
authors.initials: C
authors.lastname: Ecker
authors.forename: Lisa
authors.initials: L
authors.lastname: Page
authors.forename: Fiona
authors.initials: F
authors.lastname: Toal
authors.forename: Mary L
authors.initials: ML
authors.lastname: Phillips
authors.forename: Simon
authors.initials: S
authors.lastname: Surguladze
authors.forename: Declan G M
authors.initials: DG
authors.lastname: Murphy
mesh_terms: D000293:Adolescent; D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage; D004644:Emotions / Q000502:physiology*; D005149:Facial Expression; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology; D012701:Serotonin / Q000502:physiology; D014364:Tryptophan / Q000097:blood / Q000172:deficiency*
chemical_list: D000596:Amino Acids; D012701:Serotonin; D014364:Tryptophan