Variation in serotonin transporter expression modulates fear-evoked hemodynamic responses and theta-frequency neuronal oscillations in the amygdala.
Genetic variation in serotonin transporter expression is believed to influence emotional processing, but human studies have been inconclusive. Here we show that mice with increased serotonin transporter expression have reduced emotional learning, and that this is accompanied by altered neuronal activity in the amygdala, a brain region necessary for emotional processing.
Gene association studies detect an influence of natural variation in the 5-hydroxytryptamine transporter (5-HTT) gene on multiple aspects of individuality in brain function, ranging from personality traits through to susceptibility to psychiatric disorders such as anxiety and depression. The neural substrates of these associations are unknown. Human neuroimaging studies suggest modulation of the amygdala by 5-HTT variation, but this hypothesis is controversial and unresolved, and difficult to investigate further in humans.
2014.Biol. Psychiatry, 75(11):901-8.