Vertices, Points

In a network graph, each node is a point representing a distinct element within the system. Interactions between nodes are represented by lines or edges.

There are a two basic approaches to node definition in neuroimaging: using an undivided and unprocessed source of signal (e.g., an fMRI or MEG voxel or EEG electrode) or using an averaged (in fMRI and MEG) or spatially reconstructed (in EEG) signal localized in an anatomically or functionally based region of interest (ROI). fMRI networks built from nodes defined as individual voxels result in graphs with node counts ranging from ~5000 to ~150,000, depending on voxel size and choice (Stanley et al. 2013). This approach has been advocated due to the higher spatial resolution and potential for model-free analysis. The downsides, however, include a lower signal-to-noise ratio and increased graph size, resulting in increased analysis complexity and computational load (De Vico Fallani...