Unconscious emotional conflict in major depressive disorder: A simultaneous EEG-fMRI study

• Applicant: Professorin Dr. Ute Habel, since 6/2020
• Subject Area: Biological Psychiatry ; Human Cognitive and Systems Neuroscience ; Cognitive, Systems and Behavioural Neurobiology
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441023175

According to the cognitive model of depression, biased acquisition and evaluation of emotional information are the key elements in developing and maintaining depression. Maladaptive functions in depression are primarily explained by two mechanisms; i) hyperactive responses to negative information initiate emotional processing bias, even when the negative information has been unconsciously perceived, and ii) attenuated cognitive control impairs evaluation of the biased information. The present project aims to construct a neural model that provides separate mechanisms in clinical depression by which i) emotion processing is biased at an unconscious level and ii) the resulting effects of unconscious emotional information are controlled on a conscious level. The project proposes a technically demanding approach that provides insight into which brain regions are critically involved in the early phase of emotion processing before conscious awareness has occurred (bottom-up pathway) and how the brain responses are linked to the subsequent conscious cognitive processes (top-down pathway). Disentangling such neural effects in depression could allow for developing a more targeted and effective clinical treatment. To test the effect of unconscious emotional information on cognitive processing, the present study applies a modified backward-masked emotional conflict task to a large sample of participants (50 major depressive disorders and 50 healthy controls), in which the task paradigm ensures two distinct unconscious/conscious emotional conflict effects. Second, a multimodal neuroimaging technique is applied. The noninvasive simultaneous EEG-fMRI recording allows examining human brain activity with both high temporal and high spatial resolutions. The hemodynamic responses of the brain (fMRI) in association with neural electrical responses (EEG) are identified based on trial-by-trial correlations. MRI-informed EEG analysis also provides neural events in subcortical and cortical structures at millisecond resolution, helping to reveal the early phase of emotion processing bias before any conscious perception can occur. Third, in a proof of concept approach, the contribution of bottom-up and top-down pathways is examined using an advanced neuroimaging technique namely dynamic causal modeling. Taking the generative models that are derived from both EEG and fMRI responses, the inferred functional and directional connections in the cortical network are quantified and examined between unconscious/conscious emotional conflict effects as well as between groups. On this basis, future clinical studies could test whether the functional abnormalities in the brain to be found in major depressive disorders are also present in other mental disorders such as bipolar disorder, which may confirm unique neural markers for major depressive disorder.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Han-Gue Jo, Ph.D., until 6/2020