An inverse relationship between grey matter volumes of the OFC and measures of impulsivity has been shown in healthy adults (Matsuo et al. 2008). Children and adults with ADHD who exhibit disinhibited and impulsive behaviors have smaller OFC volumes compared with healthy subjects (Carmona et al. 2005; Hesslinger et al. 2002). Aspects of the extended limbic network have been found to be abnormal in individuals with major depression (reviewed by Drevets et al. 2008). Similarly, a meta-analysis of functional imaging studies supports a connection between increased activation of the amygdala and insula and anxiety disorders (Etkin and Wager 2007).
