Abstract
In the past years a multitude of studies has revealed alterations on a neuromolecular, structural and network level in patients with major depressive disorder within key regions of emotion and cognition processing as well as implicated neurotransmitter systems. The present review is thought to give an overview over recent developments with regard to treatment-induced changes in structural, functional and molecular neuroimaging. A number of studies could show that antidepressant treatment may lead to a partial restorage of primarily altered processes. This becomes evident in structural magnetic resonance imaging studies which point towards the reduction of volumetric differences between depressed patients and healthy controls during treatment, along with a normalization of neuronal functioning as assessed with functional magnetic resonance imaging. On a molecular level positron emission tomography studies investigating targets which are fundamentally implicated in antidepressant action such as serotonergic and dopaminergic transporters and receptors have shown to be sustainably influenced by antidepressant treatment. However, it seems that not all dysfunctional processes can be reversed by antidepressant treatment and that state and trait factors are evident not only on a behavioral but also on a neurobiological level.
About the authors

Dr. Anna Höflich is a resident at the Department of Psychiatry and Psychotherapy at the Medical University of Vienna, Austria. She is involved in a number of neuroimaging studies using fMRI and PET focusing on the analysis of neurobiological effects of pharmacological intervention and particularly the serotonergic system. Besides her clinical training she is doing her PhD in clinical neurosciences and her psychotherapeutical training.

Dr. Pia Baldinger is a resident at the Department of Psychiatry and Psychotherapy at the Medical University of Vienna, Austria. She is involved in a number of neuroimaging studies using positron emission tomography (PET) and MRI. Besides her clinical training she is doing her PhD in Clinical Neurosciences focused on Molecular Imaging Genetics.

Markus Savli, MSc studied Biomedical Engineering at the University of Applied Sciences Technikum Wien. He is working as a research assistant at the Department of Psychiatry and Psychotherapy at the Medical University of Vienna, Austria. He is involved in the analysis of molecular and functional neuroimaging data. M. Savli is an expert in PET modeling, particularly of the serotonergic system. Currently, he is writing his doctoral thesis on multi-tracer imaging of the serotonergic system at the Vienna University of Technology.

Rupert Lanzenberger is head of the Functional, Molecular and Translational Neuroimaging Lab – PET & MRI at the Department of Psychiatry and Psychotherapy of the Medical University in Vienna, Austria. He published several papers focused on molecular and functional neuroimaging in high-ranked journals (Hirsch-Index 16) and is a frequent speaker on this topic at international conferences. He serves on several scientific advisory committees and the editorial boards of five international journals. Since 2011 he is the chair of the International Task Force on Brain Imaging of the World Federation of Societies of Biological Psychiatry (WFSBP).

Dr. Siegfried Kasper is Professor of Psychiatry and Chairman of the Department of Psychiatry and Psychotherapy at the Medical University of Vienna, Austria. Dr. Kasper published 885 in ISI (http://portal.isiknowledge.com) listed publications (Citation Index: 9725, Hirsch-Index: 50) and more than 200 book chapters, in various areas of psychiatry. Dr. Kasper serves on the executive committees and advisory boards of several national and international societies. From 2005 to 2009 Dr. Kasper was President of the World Federation of Societies of Biological Psychiatry (WFSBP). He is Chief-Editor of the World Journal of Biological Psychiatry and the International Journal of Psychiatry in Clinical Practice, and Field Editor of the International Journal of Neuropsychopharmacology.
©2012 by Walter de Gruyter Berlin Boston