Higher cognitive functions require the coordination of large assemblies of
spatially distributed neurons in ever changing constellations. It is
proposed that this coordination is achieved through temporal coordination
of oscillatory activity in specific frequency bands. Since there is no
supra-ordinate command centre in the brain, the respective patterns of
synchronous activity self-organize, which has important implications on
concepts of intentionality and top down causation. Evidence will be
provided that synchronisation supports response selection by attention,
feature binding, subsystem integration, short-term memory, flexible
routing of signals across cortical networks and access to the work-space
of consciousness. The precision of synchronisation is in the millisecond
range, suggesting the possibility that information is encoded not only in
the co-variation of discharge rates but also in the precise timing of
individual action potentials. This could account for the high speed with
which cortical circuits can encode and process information. Recent studies
in schizophrenic patients indicate that this disorder is associated with
abnormal synchronisation of oscillatory activity in the high frequency
range (beta and gamma). This suggests that some of the cognitive deficits
characteristic for this disease result from deficient binding and
subsystem integration.