title: The serotonin transporter gene polymorphism and the effect of baseline on amygdala response to emotional faces.
abstract: Previous research has found that a common polymorphism in the serotonin transporter gene (5-HTTLPR) is an important mediator of individual differences in brain responses associated with emotional behaviour. In particular, relative to individuals homozygous for the l-allele, carriers of the s-allele display heightened amygdala activation to emotional compared to non-emotional stimuli. However, there is some debate as to whether this difference is driven by increased activation to emotional stimuli, resting baseline differences between the groups, or decreased activation to neutral stimuli. We performed functional imaging during an implicit facial expression processing task in which participants viewed angry, sad and neutral faces. In addition to neutral faces, we included two further baseline conditions, houses and fixation. We found increased amygdala activation in s-allele carriers relative to l-homozygotes in response to angry faces compared to neutral faces, houses and fixation. When comparing neutral faces to houses or fixation, we found no significant difference in amygdala response between the two groups. In addition, there was no significant difference between the groups in response to fixation when compared with a houses baseline. Overall, these results suggest that the increased amygdala response observed in s-allele carriers to emotional faces is primarily driven by an increased response to emotional faces rather than a decreased response to neutral faces or an increased resting baseline. The results are discussed in relation to the tonic and phasic hypotheses of 5-HTTLPR-mediated modulation of amygdala activity.
authors.affiliation: MRC Cognition and Brain Sciences Unit, Cambridge, UK. elisabeth.vondemhagen@mrc-cbu.cam.ac.uk
authors.forename: Elisabeth A H
authors.initials: EA
authors.lastname: von dem Hagen
authors.forename: Luca
authors.initials: L
authors.lastname: Passamonti
authors.forename: Sarah
authors.initials: S
authors.lastname: Nutland
authors.forename: Jennifer
authors.initials: J
authors.lastname: Sambrook
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Calder
mesh_terms: D000328:Adult; D000679:Amygdala / Q000502:physiology*; D000704:Analysis of Variance; D004644:Emotions / Q000502:physiology*; D005071:Evoked Potentials / Q000235:genetics* / Q000502:physiology; D005149:Facial Expression; D005260:Female; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008606:Mental Processes / Q000502:physiology*; D011110:Polymorphism, Genetic; D012016:Reference Values; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D055815:Young Adult
chemical_list: D050486:Serotonin Plasma Membrane Transport Proteins