Neuroimaging studies of humans with major depressive disorder have largely pointed to prefrontal sites, especially implicating an area in the midline subgenual anterior cingulate cortex, often denoted as area 25 (see the figure. Not only does this region appear abnormal on structural and functional scans, but also it is enriched with the serotonin transporter, a target for many antidepressant drugs. Individuals inheriting a risk allele within the promoter of the serotonin transporter gene have reduced volume of area 25 and reduced functional coupling of this region to the amygdala, a subcortical region implicated in the regulation of emotion. An initial study of treatment-resistant depressed patients reports that deep brain stimulation adjacent to area 25 relieves the symptoms of major depressive disorder.
Tuesday, August 21, 2007
Thomas Insel writes a perspectives article in the Aug. 10 issue of Science (PDF here) on efforts to specify brain areas that show abnormal activity during depression. A clip from his article: