Abstract
Altered brain function in patients with major depressive disorder (MDD) has been repeatedly demonstrated by task-based and resting-state studies, respectively. However, less is known concerning whether overlapped abnormalities in functional activities across modalities exist in MDD patients. To find out the answer, we implemented an fMRI experiment and collected both task and resting-state data from 19 MDD patients and 19 matched, healthy, controls. A distraction paradigm involving emotionally valenced pictures was applied to induce affective responses in subjects. As a result, concurrent deficits were found in arousing activation during a positive task in both the reward circuit and salience network (SN) that is composed of the dorsal part of anterior cingulate cortex (dACC) and bilateral anterior insulae (AI) in only the MDD group. Subsequent amplitude of low frequency fluctuations (ALFF) and functional connectivity analyses based on resting-state data exhibited consistent alterations in the bilateral AI of MDD patients, and indicated patients’ difficulties in regulating the balance between central executive network (CEN) and default mode network (DMN) due to altered connectivity among the CEN, DMN, and SN. Our findings provide new evidence demonstrating impaired salience processing and resulting alterations in responses to positive stimuli in MDD patients. Furthermore, brain abnormalities synchronized across functional states in MDD patients can be evidenced by a combination of task and resting-state fMRI analyses.
Highlights
Major depressive disorder (MDD) is characterized by emotional and cognitive impairments, such as, alterations in emotion processing, cognitive control, affective cognition, and reward processing [1,2,3,4]
We carried out two-way analyses of variance on the accuracy (ACC) and reaction time (RT) by specifying the 3 task conditions as the within-group factor (Condition) and the 2 groups as the between-group factor (Group)
Concurrent deficits in arousing activation were observed in both the reward circuit and salience network consisting of the dorsal part of anterior cingulate cortex (dACC) and bilateral anterior insula (AI) during the positive task in only the major depressive disorder (MDD) group
Summary
Major depressive disorder (MDD) is characterized by emotional and cognitive impairments, such as, alterations in emotion processing, cognitive control, affective cognition, and reward processing [1,2,3,4] Neuroimaging methods such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have provided profound insights about the neural mechanisms in MDD patients, highlighting aberrant function and interaction of cortical, subcortical, (para) limbic, and midbrain regions mediating cognition, emotion, as well as metabolism [5,6,7]. Multimodal measurement has become a powerful driver of current neuroimaging research, given its advantages in recognizing potential clinical benefits [8] It greatly improves the reliability of results, as it overcomes the limitations of individual modalities. A combination of task and resting-state fMRI was utilized to gain a panoramic view of neural activities in the brain of MDD patients by comparing of responsiveness to emotionally valenced stimuli and spontaneous neural oscillations when the brain is at rest
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