Emotions and the prefrontal cortex in depression
Neuroimaging studies demonstrated a crucial role of the prefrontal cortex in emotion processing. Changes in various prefrontal cortical regions like the medial and lateral prefrontal cortex have been observed in depression, more specifically in major depressive disorder (MDD). Though numerous imaging studies have been reported in MDD, the exact neural mechanisms associated with different depressive symptoms like anhedonia, abnormal negative cognitions, and somatic-vegetative symptoms remains unclear. Furthermore, the biochemical substrates of abnormal emotion processing remain unclear. The purpose of the presentation is to present a variety of functional imaging studies on the distinct components of emotion processing and their biochemical basis in both healthy and MDD subjects. The differential role of medial and lateral prefrontal cortical regions and their association with distinct depressive symptoms will be pointed out. Furthermore, combining fMRI with magnetoresonancespectroscopy (MRS), I will present exploratory studies of the neuronal-biochemical linkage in medial prefrontal cortex in both healthy and depressed subjects. Taken together, these studies may be considered a first step in developing a symptom-based functional neuroanatomy of MDD which ultimately will result in establishing “diagnostic markers”.