| Major Depressive Disorder (MDD) is the most widely prevalent psychiatric disorder, and yet it is not possible to predict if and when a patient will respond to medication. To improve treatment of depression it is important to increase understanding of the neurobiology of MDD and develop biomarkers of treatment response. Both of these goals may be advanced through an investigation of the rostral anterior cingulate cortex (rACC). The rACC is an integral part of the frontal-limbic network, which exhibits abnormalities in MDD, and which may predict response to treatment. The approach taken in this dissertation utilizes electroencephalographgy (EEG) source localization, which allows for tying together EEG literature with other neuroimaging modalities. Using EEG source localization we investigate the rACC and its role in the neurobiology of MDD. We show differences in EEG source localization in the rACC, among numerous other areas, between depressed patients and healthy controls. We also show that theta band current density in the rACC may predict response to antidepressant medication. Both response to treatment and rACC activity may be influenced by early improvement in symptoms, as well as prior treatment with antidepressant medication. Furthermore, we find evidence that rACC activity changes over time, and may reflect a patient's state of responsiveness to medication. Overall, this dissertation supports the idea that rACC activity provides insight into the neurobiology of MDD, and offers the possibility of improving treatment. |
