Alterations in Emotional and Salience Responses to Positive Stimuli in Major Depressive Disorder

To find out the influences on the emotionality and attentional deployment caused by depression, we recruited 19 MDD patients and 19 healthy controls, and implemented a task-state fMRI experiment using a distraction task paradigm. Our results showed relatively decreased brain activation in the right precuneus and left DLPFC, in the MDD group compared with the healthy group across the positive, neutral, and negative task conditions. During only the positive condition, decreased subcortical responses and concurrently reduced brain activation in the salience network were found only in MDD patients. Further brain-symptom analysis demonstrated significant correlation between alterations in the key region of the salience network and the depressive severity of the patients. Our findings suggest a crucial role of aberrant salience processes (especially in the anterior insulae) in the abnormal perception of positive stimuli in MDD patients, which is likely to be the underlying pathology of the anhedonia.