Anxiety related stimuli such as multiple classes of anxiogenic drugs including UCN 2, or anxiety producing situations including exposure to an open-field test arena, or social defeat, lead to increased activation of DRD serotonergic neurons as measured by c-Fos immunoreactivity (Abrams et al., 2005; Gardner et al., 2005; Bouwknecht et al., 2007; Hale et al., 2008, 2010; Paul et al., 2011). This evidence concerns the gene FOS and Anxiety.