Functional neuroimaging in mood disorders

Several brain regions are involved in emotional processing and in the integration of emotion with cognition and visceral functions. These include the prefrontal cortex, the anterior cingulated cortex, the amygdala, the parahippocampal gyrus and the hippocampus. These regions are heavily interconnected and also connected with other brain structures, particularly the thalamus, hypothalamus and striatum. Our understanding of the neural circuitry involved in mood disorders is rapidly expanding through the ever-increasing application of functional brain imaging techniques. Such techniques include positron electron tomography (PET) or single photon emission computed tomography (SPECT) and functional magnetic resonance imaging (fMRI). Compared with other techniques, fMRI offers superior temporal and spatial resolution, which allows a more accurate examination of the neural networks associated with cognitive processes. A selective review of functional neuroimaging studies in patients with primary mood disorders was undertaken in order to identify points of commonality and controversy in the existing literature.