This paper uses EEG to examine the timecourse of synchronization patterns across the brain during a simple cognitive task.  First, there was low frequency (delta) synchrony, which may reflect global, long-range synchronization and may help organize the higher frequency synchrony that followed.  Then, there was higher frequency (gamma) synchrony, which may reflect reorganization of local circuits for bottom-up processing of sensory inputs.  Finally, there was beta synchrony, which may reflect the final stage of top-down processing in the task.  Gamma and beta synchronization has been shown to be correlated with bottom-up vs top-down cortical processing (Buschman and Miller, 2007; Chanes et al, 2013; Ibos et al, 2013).  This study identifies and confirms some of the proposed mechanisms of global information integration in the brain.
Brazdil et al (2013)

For further reading:
Buschman, T.J. and Miller, E.K. (2007) Top-down versus bottom-up control of attention in the prefrontal and posterior parietal cortices. Science. 315: 1860-1862  The Scientist’s “Hot Paper” for October 2009. View PDF »

Chanes et al (2013)  Journal of Neuroscience

Ibos et al (2013) Journal of Neuroscience