BDNF and depressive symptom measurement: Contrary to a BDNF perspective of stressor-induced depression, however, BDNF elevations in the mPFC, amygdala, and substantia nigra have been reported after intermittent social defeat (Fanous et al., 2010), as well as in the neocortex and the nucleus accumbens after a chronic social stressor (Berton et al., 2006; Schulte-Herbrüggen et al., 2009).