Default Mode Network and Neural Phase Synchronization in Healthy Aging: A Resting State EEG Study

Area of Science:

• Neuroscience
• Cognitive Aging
• Electrophysiology

Background:

• Aging impacts brain connectivity, particularly within the default mode network (DMN).
• Previous research primarily used fMRI; electrophysiological correlates of DMN connectivity changes in aging are less understood.
• The relationship between DMN functional connectivity and cognitive performance in older adults requires further investigation.

Purpose of the Study:

• To investigate age-related differences in electrophysiological measures of DMN functional connectivity during resting state.
• To specifically examine connectivity between the medial prefrontal cortex (mPFC) and other DMN regions.
• To correlate these connectivity patterns with cognitive performance in older adults.

Main Methods:

• Electroencephalography (EEG) recorded from younger and older adults during resting state conditions.
• Source-level functional connectivity quantified using phase-locking value (PLV) across a wide frequency range (1-50 Hz).
• Cognitive assessments included memory, language, executive functioning, and processing speed.

Main Results:

• Older adults exhibited decreased alpha2-band connectivity between the mPFC and regions like the left angular gyrus and lateral temporal cortices.
• This decreased connectivity correlated with lower performance in semantic fluency and executive functioning in older adults.
• Increased theta and beta band PLV were observed between the mPFC and posterior cingulate in older adults compared to younger adults.

Conclusions:

• Age-related changes in DMN functional connectivity are frequency-dependent and non-uniform.
• Specific alterations in DMN connectivity, particularly in the alpha2 band, are associated with cognitive decline in older adults.
• Electrophysiological measures provide valuable insights into the neural underpinnings of cognitive aging.