[Neuroimaging studies of depression: Current status and future direction.]

Recent advances in neuroimaging studies enable us to measure brain function non-invasively. Over the past several decades, neuroimaging measurement has been substantially applied to elucidate the neurobiological mechanisms underlying major depressive disorder (MDD). Since MDD is a wide spectrum which consists of various symptoms such as low mood or loss of interest and is considered to affect a biologically het- erogeneous population, we have not yet elucidated the biological underpinnings of MDD. It seems to be more promising to consider MDD as an integral network abnormality instead of deficits in specific brain regions or neurotransmitters. We firstly provide a comprehensive review of the extant neuroimaging literature including structural and functional magnetic resonance imaging, magnetic resonance spectroscopy, single pho- ton emission computed tomography, and positron emission tomography studies. Then we show our neuroimaging studies for MDD toward po- tential application as a biomarker for diagnosis and treatment. We believe it will facilitate the development, of a more integrative model of neural dysfunction in MDD.