  Selective attention allows to process stimuli which are behaviorally
relevant, while attenuating distracting information. However, it is an open
question what mechanisms implement selective routing, and how they are engaged
in dependence on behavioral need. Here we introduce a novel framework for
selective processing by spontaneous synchronization. Input signals become
organized into 'avalanches' of synchronized spikes which propagate to target
populations. Selective attention enhances spontaneous synchronization and
boosts signal transfer by a simple disinhibition of a control population,
without requiring changes in synaptic weights. Our framework is fully
analytically tractable and provides a complete understanding of all stages of
the routing mechanism, yielding closed-form expressions for input-output
correlations. Interestingly, although gamma oscillations can naturally occur
through a recurrent dynamics, we can formally show that the routing mechanism
itself does not require such oscillatory activity and works equally well if
synchronous events would be randomly shuffled over time. Our framework explains
a large range of physiological findings in a unified framework and makes
specific predictions about putative control mechanisms and their effects on
neural dynamics.
