Frequency specific interactions of MEG resting state activity within and across brain networks as revealed by the multivariate interaction measure

Abstract

Resting state networks (RSNs) are sets of brain regions exhibiting temporally coherent activity fluctuations in the absence of imposed task structure. RSNs have been extensively studied with fMRI in the infra-slow frequency range (nominally < 10−1 Hz). The topography of fMRI RSNs reflects stationary temporal correlation over minutes. However, neuronal communication occurs on a much faster time scale, at frequencies nominally in the range of 100 – 102 Hz. We examined phase-shifted interactions in the delta (2–3.5 Hz), theta (4–7 Hz), alpha (8–12 Hz) and beta (13–30 Hz) frequency bands of resting-state source space MEG signals. These analyses were conducted between nodes of the dorsal attention network (DAN), one of the most robust RSNs, and between the DAN and other networks. Phase shifted interactions were mapped by the Multivariate Interaction Measure (MIM), a measure of true interaction constructed from the maximization of imaginary coherency in the virtual channels comprised of voxel signals in source space. Non zero-phase interactions occurred between homologous left and right hemisphere regions of the DAN in the delta and alpha frequency bands. Even stronger non zero-phase interactions were detected between networks. Visual regions bilaterally showed phase-shifted interactions in the alpha band with regions of the DAN. Bilateral somatomotor regions interacted with DAN nodes in the beta band. These results demonstrate the existence of consistent, frequency specific phase-shifted interactions on a millisecond time scale between cortical regions within RSN as well as across RSNs.

Dynamics of EEG Rhythms Support Distinct Visual Selection Mechanisms in Parietal Cortex: A Simultaneous Transcranial Magnetic Stimulation and EEG Study

“…Although its generators are still not well known, the ␣ power is most consistently localized in parieto-occipital cortex (Vanni et al, 1997), as well as in the ventral visual stream (Snyder and Foxe, 2010). Spontaneous oscillations of ␣ power have been also recently associated with excitability of occipital cortex to visual stimulation (Romei et al, 2008). In particular, when attention is directed to a peripheral spatial location, ␣ EEG rhythms in parieto-occipital cortex desynchronize contralaterally to the attended location (Worden et al, 2000;Yamagishi et al, 2003;Thut et al, 2006;Jensen et al, 2012).…”

“…Spontaneous oscillations of ␣ power have been also recently associated with excitability of occipital cortex to visual stimulation (Romei et al, 2008). In particular, when attention is directed to a peripheral spatial location, ␣ EEG rhythms in parieto-occipital cortex desynchronize contralaterally to the attended location (Worden et al, 2000;Yamagishi et al, 2003;Thut et al, 2006;Jensen et al, 2012). Moreover, a recent study suggested a role of anticipatory ␣ oscillations in establishing and maintaining an active task set, with the contralateral posterior ␣ activity as a neural marker of the on-line maintenance of the stimulus-response association ( Grent-'t-Jong et al, 2013 2006), leads to a disruption of parieto-occipital ␣ topography (Capotosto et al, 2009(Capotosto et al, , 2012.…”

“…To assess the physiological impact of rTMS on anticipatory neural activity, we recorded simultaneously EEG activity from the scalp. Specifically, we measured the effect of magnetic stimulation delivered over different cortical loci on the peak latency and amplitude of EEG rhythm synchronization/desynchronization measured over the parieto-occipital and frontocentral regions, a reliable physiological index of anticipatory spatial attention modulation (Worden et al, 2000;Yamagishi et al, 2003;Sauseng et al, 2005;Thut et al, 2006). EEG data were recorded (bandpass, 0.05-100 Hz; sampling rate, 256 Hz; AC couple mode recording; BrainAmp, Brain Products) from 64 EEG electrodes placed according to an augmented 10-20 system, and mounted on an elastic cap resistant to magnetic pulses.…”

“…Specifically a desynchronization of the occipitoparietal ␣ rhythms is typically observed in the hemisphere contralateral to the attended visual field before target presentation (Worden et al, 2000;Yamagishi et al, 2003;Kelly et al, 2006Kelly et al, , 2009Thut et al, 2006). Moreover, increased power at lower frequencies (i.e., ␦, 2-4 Hz; , 4 -8 Hz) has been reported over frontocentral regions following the presentation of attention cues (Klimesch, 2012;Daitch et al, 2013).…”

Measuring temporal, spectral and spatial changes in electrophysiological brain network connectivity

“…Here we focus only on application of CCA across multiple voxels, however this may be further extended to multiple frequency bands within 33 each voxel, or multiple current orientations within each voxel. The latter case is of particular interest and has been used successfully in a recent study to explore signal coherence in the dorsal attention network (Marzetti et al, 2013). To summarise, our current knowledge of resting state networks is based on assumptions of stationarity; it is reasonable to assume that these are in turn simply dominant modes of a complex series of interactions which this methodology will allow us to explore.…”