Aberrant brain dynamics in major depressive disorder during working memory task

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Science

Background:

• Working memory (WM) deficits are a key endophenotype candidate for major depressive disorder (MDD).
• The precise temporal-spatial brain dynamics underlying WM deficits in MDD remain poorly understood.

Purpose of the Study:

• To investigate the whole-brain temporal-spatial profile of WM deficits in MDD using dynamical degree centrality (dDC).
• To explore group differences in dDC temporal variability and meta-stable brain states during varying WM loads.

Main Methods:

• fMRI data from 40 MDD patients and 40 controls during a 2-back and 0-back task.
• Analysis of dDC temporal variability and meta-stable states.
• Pearson's correlation to link brain dynamics with clinical symptoms and WM performance.

Main Results:

• MDD patients exhibited significantly elevated dDC variability in regions including the middle frontal gyrus, inferior frontal gyrus orbital part (IFGorb), hippocampus, and middle temporal gyrus.
• Increased dDC variability in the hippocampus and IFGorb was correlated with worse WM performance.
• No significant group differences were found in meta-stable brain states.

Conclusions:

• MDD is characterized by increased WM-related brain instability, indicated by elevated dDC variability.
• Brain activity instability in specific regions like the hippocampus and IFGorb is linked to impaired WM function in MDD.
• Strategies to enhance brain activity stability may improve WM performance in individuals with MDD.