Altered EEG Theta and Alpha Band Functional Connectivity in Mild Cognitive Impairment During Working Memory Coding

Area of Science:

• Neuroscience
• Cognitive Science
• Medical Imaging

Background:

• Mild cognitive impairment (MCI) represents a preclinical stage of Alzheimer's disease (AD).
• MCI is associated with a decline in visual working memory (WM) functions.
• Understanding the neural mechanisms of WM deficits in MCI is crucial for early intervention.

Purpose of the Study:

• To investigate differences in functional brain connectivity during visual WM coding between MCI patients and normal controls (NC).
• To identify specific network alterations associated with MCI using electroencephalography (EEG).

Main Methods:

• Acquired 32-channel EEG data from 21 MCI patients and 20 NC during a visual WM task (load four).
• Applied spectral Granger causality and Directed Transfer Function (DTF) to analyze functional connectivity.
• Utilized large-scale network analysis to compare brain network properties between groups.

Main Results:

• MCI patients exhibited reduced frontal-temporal connectivity in the theta (4-7Hz) band compared to NC.
• MCI patients showed compensatory increased frontal-occipital and parietal-occipital connectivity in theta and alpha (8-13Hz) bands.
• Significant differences in network core node out-degree were observed in frontal and parietal lobes, particularly in the theta band.

Conclusions:

• MCI is characterized by dysconnectivity from the prefrontal to temporal lobes, with compensatory recruitment of other brain regions.
• The findings highlight altered EEG dynamics and neural mechanisms underlying WM deficits in MCI.
• Identified potential therapeutic targets within the identified dysconnectivity patterns for clinical intervention.