Analysis of magnetoencephalography signals from Alzheimer's disease patients using granger causality

The aim of this study was to analyze resting-state magnetoencephalography (MEG) activity in Alzheimer's disease (AD) by means of Granger Causality (GC), an effective connectivity measure that provides an estimation of the information flow between brain regions. For this task, five minutes of MEG recordings were acquired with a 148-channel whole-head magnetometer from 36 AD patients and 26 healthy controls. Abnormalities in AD connectivity were found in the five typical frequency bands: delta (δ, 1-4 Hz), theta (θ, 4-8 Hz), alpha (α, 8-13 Hz), beta (β, 13-30 Hz), and gamma (γ, 30-65 Hz). Noteworthy increments in delta band and decrements in beta and gamma bands revealed disrupted connections in AD brain activity. Our analyses suggest that GC may be useful to characterize the brain impairment in AD.