Hierarchical Control of Multi-Frequency Band Activity

EEG activity can indicate different states of meso- to macro-level neural systems in the brain, according to the frequency band.  Cross-scale coordination processes may be studied by investigating the coupling of activity between these bands (Canolty et al., 2006; Demiralp et al., 2007; Nakatani et al., submitted; Saesung et al., 2008).  Possible functional roles for these couplings have been discussed (Lakatos, et al., 2008; Schroeder & Lakatos, 2009; Lismann & Ideart, 1995), but their underlying mechanism still needs to be determined. Lakatos and colleagues (2008 and 2009) proposed the Hierarchical Control (HC) theory, in which slower activity controls faster ones in a nested manner, e.g. alpha is controlled by theta; theta is controlled by delta; the latter, the slowest oscillations, are in turn controlled by, for instance, the task. Accordingly, Lakatos et al. (2005) showed that the phase of delta band activity was entrained to the timing of attended stimuli.  In addition, observations on coupling of high frequency oscillations and low-frequency ones have been interpreted as evidence for HC theory.  It is an open question, however, whether the coupling is nested.  In this Ph. D. project, we will perform analyses on previously collected data in order to find out which couplings exist in real data, and whether they are hierarchically nested.  The observed couplings will be fitted to a set of dynamical models for multi-band activity (e.g., Kopell et al.; 2011, Chik, 2013) or, if necessary, such models will be developed.