Neural response to pleasant stimuli in anhedonia: an fMRI study

The aim of this study was to investigate the neural correlates of affect processing in depressed anhedonic patients and healthy controls. Whole brain functional magnetic resonance imaging scans were obtained from seven females with a diagnosis of chronic unipolar major depression and high levels of anhedonia, and seven healthy females, while they were presented with positive valence and neutral images. Patients, compared to controls, showed decreased activation in medial frontal cortex, and increased activation in inferior frontal cortex, anterior cingulate, thalamus, putamen and insula. Reduced activation in medial frontal cortex may underlie abnormal positive affect processing in patients. Increases in neural activation in putamen and thalamus, previously found in transient sadness, and anterior cingulate could point to an involvement of these structures in anhedonia.