Directed interregional brain interactions

Abstract

Large-scale network coordination in the healthy brain is a manifestation of brain areas working together to achieve a functional goal. The cognitive behavior of brain networks is revealed by the relative timing of coordinated brain areas during cognitive task performance (Bressler and Kelso 2016). Coordination of brain areas has been demonstrated by function-related phase synchrony of the EEG, MEG, iEEG, ECoG, or LFP at a fast timescale in the 1-200 Hz frequency range where these signals commonly show brain activity, and by time series modeling of fMRI BOLD signal interactions at a slow timescale (Bressler et al. 2008; Tang et al. 2012; Asemi et al. 2015; Silverstein et al. 2016; Meehan et al. 2017; Diwadkar et al. 2017). From phase synchrony to interregional interaction to large-scale network coordination, an emerging view of brain function sees large-scale systems of distributed and interconnected neuronal populations in the central nervous system, or neurocognitive networks, as uniquely organized to perform specific cognitive functions. Simply put, specific cognitive functions are executed by uniquely configured neurocognitive networks. Following graph theory, neurocognitive networks are modeled as network nodes and edges, in a similar manner to other kinds of networks. Edges in neurocognitive networks are commonly demonstrated by showing a consistent between-area relative phase relation between network nodes at the fast timescale, or by a significant correlation of network nodes at the slow timescale. However, they ultimately depend on directed interactions that transpire between brain regions. This chapter focuses on directed interregional interactions in neurocognitive networks as the basis for cognitive function.