Consistent Brain Entropy Changes During Rumination Across Three Magnetic Resonance Imaging Scanners

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychiatry

Background:

• Rumination, repetitive self-referential thinking, is linked to depression and psychiatric disorders.
• Previous research often used task activation or network-level analyses, missing local brain activity dynamics during rumination.

Purpose of the Study:

• To investigate local brain activity patterns during rumination using brain entropy (BEN).
• To explore the neural mechanisms underlying rumination and its relation to cognitive states.

Main Methods:

• Utilized functional magnetic resonance imaging (fMRI) to measure brain entropy (BEN), quantifying local brain activity complexity.
• Analyzed data from 41 healthy adults across three scanners under resting state, sad memory, rumination, and distraction conditions.
• Conducted voxel-wise BEN analyses to identify significant condition-related differences in brain regions.

Main Results:

• Rumination showed decreased BEN in the visual cortex (VC) compared to sad memory.
• Distraction exhibited decreased BEN in the posterior cingulate cortex/precuneus (PCC/PCu).
• Rumination demonstrated increased BEN in the PCC/PCu relative to distraction, indicating heightened temporal irregularity in self-referential processing regions.

Conclusions:

• Brain entropy (BEN) effectively reveals distinct neural signatures of cognitive states.
• Rumination is characterized by increased temporal complexity in self-referential brain regions and reduced engagement with external information.
• Findings support the utility of BEN for understanding rumination and developing neuroimaging biomarkers for depression.