Functional connectivity in mild cognitive impairment during a memory task: implications for the disconnection...

Area of Science:

• Neuroscience
• Cognitive Science

Background:

• Mild cognitive impairment (MCI) is an intermediate stage between healthy aging and dementia.
• Early Alzheimer's disease involves connectivity damage and synaptic loss, suggesting MCI might be a disconnection syndrome.

Purpose of the Study:

• To compare brain signal synchronization in MCI patients versus healthy controls during a memory task.
• To investigate functional connectivity patterns in MCI and their relation to the disconnection syndrome hypothesis.

Main Methods:

• Magnetoencephalography (MEG) recorded brain signals from 22 MCI patients and 19 healthy controls.
• Synchronization Likelihood, a nonlinear dynamical systems index, quantified functional connectivity.
• Analysis focused on interhemispheric and regional synchronization across different frequency bands during a memory task.

Main Results:

• MCI patients showed higher interhemispheric synchronization in temporo-frontal and posterior (gamma band) regions compared to controls.
• Healthy controls exhibited higher synchronization within left temporal and central regions across all bands.
• Controls had greater Synchronization Likelihood than MCI patients in central-posterior and frontal-posterior connections (gamma band).

Conclusions:

• Increased interhemispheric synchronization in MCI may represent a compensatory mechanism for network inefficiency.
• The findings partially support the disconnection syndrome hypothesis for MCI, showing increased long-distance connections but decreased antero-posterior connectivity.