This appears to represent an effect of this locus on emotional response and resiliency, as has been shown via neuroimaging studies revealing altered amygdala fMRI response to emotional probes and altered connectivity between the amygdala and brain regions that modulate amygdala response, with that connectivity predicting depressive symptoms. Caspi et al found that individuals who had the 5-HTTLPR S allele and had also experienced childhood trauma or stressful life events after 21 years of age had an increase in depressive symptoms, whereas the l/l homozygotes did not. Since that publication, additional replications and extensions of this finding have been published aswell as studies that have failed to confirm these findings.