Complex activities require the smooth cooperation of wide apart brain areas. In the flow, this collaboration works particularly effectively.

EEG-Study on the Neurobiology of Flow-States
in Musicians, Bremen – Novosibirsk 2005

In an exploratory study, the brain waves of students from the University of the Arts Bremen and the Novosibirsk Conservatory were measured during Practising in Flow. The following EEGs show the activity in the alpha frequency band:

Strong alpha activity means acting in a the state of relaxed alertness, increased performance, increased learning ability, high concentration and absorption in a task. The right mixture of serenity, inner clarity, commitment and dynamic.

High coherence. The yellow-labeled areas show a similar to same activity in the corresponding brain areas. This phenomenon is called coherence. In highly coherent states, brain regions even if located far apart communicate and cooperate optimally with each other. The brain becomes permeable to creative ideas and spontaneous problem solving. Highly coherent states are associated with positive emotions and the release of endorphins (body-owned opiates).

The brain does not oscillate in unison, at each electrode a different electrical activity is shown, the individual brain regions do not cooperate optimally, each “does what it wants”. Poorly coordinated brain activity means reduced effectiveness in thinking and acting, limited learning ability and performance.

Further studies on flow conditions in athletes and musicians:

Synchronization of the hemispheres of the brain. In golfers in hightened performance conditions, the activity in both hemispheres synchronizes, the different qualities of both hemispheres of the brain work optimally together in the management of complex tasks.

Economization of brain activity. Only the centers fire that are needed to perform a task (red/yellow), all other areas are largely deactivated (green/blue). This explains the lightness, efficiency and elegance of action in flow.
Source: www.drdebbiecrews.com

The brain of jazz pianists during improvisation shows a large deactivation of the cognitive control functions of the prefrontal brain (blue), while at the same time increasing activation of all sensory and areas responsible for genuine self-expression (red). This ensures increased permeability of the brain for creative ideas and their immediate implementation.

In contrast, brain activation during the structured scale exercise is exactly the opposite: the cognitive control functions of the prefrontal brain are activated, the activity of the sensory and the centers responsible for self-expression is reduced.
Source: Charles Limb, Allen Braun 2008, Neural substrates...