ARTICLE UPDATE - Activity and Connectivity of Brain Mood Regulating Circuit in Depression: A Functional Magnetic Resonance Study

Amit Anand, Yu Li, Yang Wang, Jingwei Wu, Sujuan Gao, Lubna Bukharia, Vincent P. Mathews, Andrew Kalnin and Mark J. Lowe

Biological Psychiatry, 57, 1079-1088

Background
Functional imaging studies indicate that imbalances in cortico-limbic activity and connectivity may underlie the pathophysiology of MDD. In this study, using functional Magnetic Resonance Imaging (fMRI), we investigated differences in cortico-limbic activity and connectivity between depressed patients and healthy controls.

Methods
Fifteen unmedicated unipolar depressed patients and 15 matched healthy subjects underwent fMRI during which they first completed a conventional block-design activation experiment in which they were exposed to negative and neutral pictures. Next, low frequency blood oxygenation dependent (BOLD) related fluctuations (LFBF) data were acquired at rest and during steady-state exposure to neutral, positive and negative pictures. LFBF correlations were calculated between anterior cingulate cortex (ACC) and limbic regions – amygdala (AMYG), pallidostriatum (PST) and medial thalamus (MTHAL) and used as a measure of cortico-limbic connectivity.

Results
Depressed patients had increased activation of cortical and limbic regions. At rest and during exposure to neutral, positive, and negative pictures cortico-limbic LFBF correlations were decreased in depressed patients compared to healthy subjects.

Conclusions
The finding of increased activation of limbic regions and decreased LFBF correlations between ACC and limbic regions is consistent with the hypothesis that decreased cortical regulation of limbic activation in response to negative stimuli may be present in depression.