Scientists Think They Finally Cracked the Flow State | by Katrina Paulson | Medium

"what causes the flow state, and what happens in the brain... a new study claims to have answers".

There were 2 theories:

• "Hyperfocus... two brain networks unlock the flow state: the default mode network (DMN)... involved in things like daydreaming... spikes the most when we’re not engaged in any tasks" and "the executive control network (ECN), which is most active during complex cognitive tasks... especially active during the creative process". So flow = ECN keeping DMN focused on generating ideas for a specific task.
• "Expertise + Letting Go:... as a person gains expertise ... [it] creates a new neural network dedicated to that activity ... the ECN takes a break from its supervisory role so a person can “let go” during the activity and allow this other specialized network to perform without interruption"

The second theory looks right in the light of the study, which tested novice and experienced jazz musicians wearing electroencephalogram (EEG) caps as they improvised musically.

The implication: "productive flow states can be attained by practice to build up expertise in a particular creative outlet coupled with training to withdraw conscious control when enough expertise has been achieved... to stream ideas fluently, then keep working on those musical scales, physics problems, or whatever else you want to do creatively ... But then, try letting go.”