Emotion specific modulation of automatic amygdala responses by 5-HTTLPR genotype

Area of Science:

• Neuroscience
• Genetics
• Psychiatry

Background:

• The serotonin transporter gene-linked polymorphic region (5-HTTLPR) is linked to amygdala reactivity.
• Previous research suggests 5-HTTLPR modulates responses to negative environmental cues.
• It is unclear if this effect is specific to negative stimuli or broader emotional salience.

Purpose of the Study:

• To investigate whether 5-HTTLPR influences amygdala responses to negative stimuli specifically or to emotionally salient stimuli generally.
• To examine the interaction between 5-HTTLPR genotype and emotional facial expression processing.

Main Methods:

• fMRI scans were used to assess amygdala responses in 44 healthy subjects.
• Subjects viewed subliminally presented happy and sad facial expressions.
• Genotyping for 5-HTTLPR and 5-HTT rs25531 was performed.

Main Results:

• A significant emotion by genotype interaction was found in the right amygdala.
• Risk allele carriers (S or L(G)) showed heightened amygdala responses to sad faces compared to L(A)L(A) homozygotes.
• No significant difference in amygdala response to happy faces was observed between genotype groups.

Conclusions:

• 5-HTTLPR genotype predominantly affects the processing of negative environmental cues.
• The genetic variation does not appear to modulate responses to all emotionally salient stimuli.
• Right amygdala activity is specifically influenced by 5-HTT gene variation in response to negative facial stimuli.