A Comprehensive Review of Magnetoencephalography (MEG) Studies for Brain Functionality in Healthy Aging and Alzheimer's Disease (AD)

Abstract

Neural oscillations were established with their association with neurophysiological activities and the altered rhythmic patterns are believed to be linked directly to the progression of cognitive decline. Magnetoencephalography (MEG) is a non-invasive technique to record such neuronal activity due to excellent temporal and fair amount of spatial resolution. Single channel, connectivity as well as brain network analysis using MEG data in resting state and task-based experiments were analyzed from existing literature. Single channel analysis studies reported a less complex, more regular and predictable oscillations in Alzheimer's disease (AD) primarily in the left parietal, temporal and occipital regions. Investigations on both functional connectivity (FC) and effective (EC) connectivity analysis demonstrated a loss of connectivity in AD compared to healthy control (HC) subjects found in higher frequency bands. It has been reported from multiplex network of MEG study in AD in the affected regions of hippocampus, posterior default mode network (DMN) and occipital areas, however, conclusions cannot be drawn due to limited availability of clinical literature. Potential utilization of high spatial resolution in MEG likely to provide information related to in-depth brain functioning and underlying factors responsible for changes in neuronal waves in AD. This review is a comprehensive report to investigate diagnostic biomarkers for AD may be identified by from MEG data. It is also important to note that MEG data can also be utilized for the same pursuit in combination with other imaging modalities.

EEG spectral power abnormalities and their relationship with cognitive dysfunction in patients with Alzheimer's disease and type 2 diabetes

“…We chose not to include EEG-measured γ because it is often contaminated by muscle (Whitham et al, 2007) and eye-movement artifacts (Yuval-Greenberg et al, 2008). An optimal approach to investigate pathophysiological signatures of γ activity in future studies would be to employ magnetoencephalography, in which cerebral γ activity can be more clearly and robustly identified than in EEG (Mandal et al, 2018).…”

Postoperative oscillatory brain activity as an add-on prognostic marker in diffuse glioma

“…A cohort of healthy controls, previously described in the setting of studies on multiple sclerosis, was used to normalize indices of broadband power [15,16]. The healthy subjects were group-level matched to the glioma patients with respect to age, as we know this can affect brain activity [17,18]. Data collection in both patients and healthy controls was approved by the ethical review board of the VUmc.…”

Alterations in resting-state network dynamics along the Alzheimer’s disease continuum: a combined MEG-PET/MR approach

“…This means that subtle AD-related changes in neural dynamics will less likely be detected with fMRI 35 . This explains why electrophysiological techniques such as magnetoencephalography (MEG) are increasingly recognized as potentially valuable markers in AD 36,37 . MEG is a non-invasive neuroimaging technique measuring the extra-cranial magnetic fields produced by electrical neural activity 38 .…”