The Functional Importance of Rhythmic Activity in the Brain

Oscillations in brain activity have long been known, but
many fundamental aspects of such brain rhythms, particularly
their functional importance, have been unclear. As we
review here, new insights into these issues are emerging
from the application of intervention approaches. In these
approaches, the timing of brain oscillations is manipulated
by non-invasive brain stimulation, either through sensory
input or transcranially, and the behavioural consequence
then monitored. Notably, such manipulations have led to
rapid, periodic fluctuations in behavioural performance,
which co-cycle with underlying brain oscillations. Such
findings establish a causal relationship between brain
oscillations and behaviour, and are allowing novel tests
of longstanding models about the functions of brain
oscillations.