Loading...
Artificial bright light treats seasonal depression, but its mechanism is unclear. To investigate whether the treatment acts on a corticolimbic threat recognition system involving the amygdala and medial prefrontal cortex (mPFC), investigators in Denmark with some industry support genotyped 30 normal men for polymorphisms in the gene for the serotonin transporter promoter (5-HTTLPR), exposed them to 30 minutes of morning bright light at various intensities (mean, 3500 lux) for 3 weeks, and performed functional magnetic resonance imaging before and after treatment as participants examined pictures of angry, fearful, and neutral faces.
In a dose-dependent manner, bright light reduced mPFC and bilateral amygdala reactivity to angry and fearful f…