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Brain Res. 2016 Mar 15;1635:143-52. doi: 10.1016/j.brainres.2016.01.043. Epub 2016 Feb 1.

Large-scale network-level processes during entrainment.

Author information

1
Center for Mind/Brain Sciences, CIMeC, University of Trento, via delle Regole 101, Mattarello 38122, Italy; Center for Cognitive Neuroscience, University of Salzburg, Hellbrunnerstraße 34/II, Salzburg 5020, Austria. Electronic address: chrysoula.lithari@sbg.ac.at.
2
Center for Mind/Brain Sciences, CIMeC, University of Trento, via delle Regole 101, Mattarello 38122, Italy. Electronic address: carolina.sanchez@unit.it.
3
Center for Cognitive Neuroscience, University of Salzburg, Hellbrunnerstraße 34/II, Salzburg 5020, Austria. Electronic address: philipp.ruhnau@sbg.ac.at.
4
Center for Mind/Brain Sciences, CIMeC, University of Trento, via delle Regole 101, Mattarello 38122, Italy; Center for Cognitive Neuroscience, University of Salzburg, Hellbrunnerstraße 34/II, Salzburg 5020, Austria. Electronic address: nathan.weisz@sbg.ac.at.

Abstract

Visual rhythmic stimulation evokes a robust power increase exactly at the stimulation frequency, the so-called steady-state response (SSR). Localization of visual SSRs normally shows a very focal modulation of power in visual cortex and led to the treatment and interpretation of SSRs as a local phenomenon. Given the brain network dynamics, we hypothesized that SSRs have additional large-scale effects on the brain functional network that can be revealed by means of graph theory. We used rhythmic visual stimulation at a range of frequencies (4-30 Hz), recorded MEG and investigated source level connectivity across the whole brain. Using graph theoretical measures we observed a frequency-unspecific reduction of global density in the alpha band "disconnecting" visual cortex from the rest of the network. Also, a frequency-specific increase of connectivity between occipital cortex and precuneus was found at the stimulation frequency that exhibited the highest resonance (30 Hz). In conclusion, we showed that SSRs dynamically re-organized the brain functional network. These large-scale effects should be taken into account not only when attempting to explain the nature of SSRs, but also when used in various experimental designs.

KEYWORDS:

Entrainment; Functional connectivity; Global density; Graph theory; Node degree; Seeded connectivity; Visual steady-state

PMID:
26835557
PMCID:
PMC4786120
DOI:
10.1016/j.brainres.2016.01.043
[Indexed for MEDLINE]
Free PMC Article

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