This paper discusses how the serotonin transporter gene (5-HTT) S allele, previously thought to confer risk, may actually confer plasticity. The study found that while S allele carriers learned fear conditioning faster with a negative attention bias modification (ABM) technique, their attention systems were also more receptive to a positive ABM technique. This provides evidence that the S allele confers neural plasticity rather than vulnerability alone. The study measured reaction times, errors, anxiety, and depression before and after using ABM techniques to induce either a threat or benign attention bias in participants. Results demonstrated that anxiety and depression increased following a negative ABM, but were reduced in S allele carriers following a positive ABM.

1. Paper review:

2. Serotonin Transporter gene is ‘plastic’
• If 5-HTT S allele is bad, why do we have it?
• It has been argued that evolution has conserved
the risk S allele because social context changes
the outcome of genetic factors
• That is, plastic neural circuits lead to negative
outcomes under detrimental conditions but to
positive outcomes under supportive conditions
• The S-allele holders learn faster fear conditioning,
thus, are more sensitive to fear-related cues

3. Attention Bias Modification
• It has been demonstrated that selective
attention biases can be modified by a simple
computerised technique
• Induction of threat bias leads to increased
stress reactivity
• Induction of benign bias leads to reduction in
emotional vulnerability

4. Methods
• Phase 1: Presented either positive or negative pictures that
preceded the target location at 50% chance
• Fixation cross (”+”) for 500 ms
• Followed by a pair of positive and negative pictures for 500
ms
• This was followed by a horizontal (..) or vertical (:) target dots
• Response: indicate whether the target is vertical or
horizontal
• Phase 2: same as before but 100% contingency (either for
negative or positive pictures)
• Phase 3: same as Phase 1 but old and new pictures employed

5. Dependent Variable
• Reaction Time and Errors
• State-anxiety questionnaire
• 2 VAS scales
• Beck’s depression inventory

6. Results & Discussion
• Changes in attention bias after the negative ABM
was greater in people with the S allele
o People with the risk allele are faster to learn fear
and develop lower sensitivity to threat threshold
• However, the attention systems of the S allele
holders are more receptive to the positive ABM too.
oEvidence for plasticity gene rather than
vulnerability gene
• Anxiety and depression levels increased following
ABM

7. Results & Discussion
• Changes in attention bias after the negative ABM
was greater in people with the S allele
o People with the risk allele are faster to learn fear
and develop lower sensitivity to threat threshold
• However, the attention systems of the S allele
holders are more receptive to the positive ABM too.
oEvidence for plasticity gene rather than
vulnerability gene
• Anxiety and depression levels increased following
ABM