In the latter, ICMs might interact with task-related coupling modes, resulting in a matching of predictions with incoming signals and a computation of error signals. In the former, in contrast, ICMs might serve to replay and consolidate the results of previous processing and to shield neural Y-27632 clinical trial populations from getting involved in the task-related coupling modes, thus preventing previous contents from being overwritten. Therefore, it would be interesting to investigate ICMs in subnetworks not engaged in a task, in the presence of task-related coupling modes in other brain networks. To further corroborate

the functional relevance of ICMs, it will be highly relevant to manipulate envelope ICMs or phase ICMs in a specific manner and to test the effects on task- or stimulus-related processing. A number of different approaches may be viable to shape ICMs. One possibility is to modulate ICMs by neuropharmacological intervention, which has been demonstrated for BOLD coupling (Wang et al., 2011b, Cole et al., 2013 and Pa et al., 2013) but not yet been applied to modulating phase ICMs in humans. Moreover, training through I-BET151 mw neurofeedback can be employed to shape ICMs. Several studies have demonstrated effects of neurofeedback on BOLD-defined envelope

ICMs (Koush et al., 2013 and Haller et al., 2013). A recent MEG study has explored the possibility to shape movement-related cross-hemispheric phase coupling by neurofeedback (Sacchet et al., 2012), suggesting that this might also be possible all for ongoing activity. A third line of approaches

is provided by noninvasive neurostimulation techniques, such as transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), or transcranial alternating current stimulation (tACS), which all have been used to modulate ongoing activity in recent studies (Paulus, 2011, Thut et al., 2012, Grefkes and Fink, 2012, Schulz et al., 2013 and Herrmann et al., 2013). Attempts to entrain envelope ICMs have been made using slowly varying tDCS, demonstrating effects on plasticity during sleep (Marshall et al., 2006) and on neuronal excitability during wakefulness (Groppa et al., 2010). Modulation of phase ICMs has been achieved by multifocal TMS in a study demonstrating enhanced alpha- and beta-band coherence following synchronous TMS stimulation over visual and motor cortex (Plewnia et al., 2008). For modulation of phase ICMs, tACS seems particularly promising because it opens up the possibility of entraining ongoing activity in a frequency-specific way (Herrmann et al., 2013). This is suggested by a recent study that has demonstrated an influence of entraining gamma-band ICMs on bistable visual perception (Strüber et al., 2013).