Deep Learning Neurochemistry:

Huberman notes that to attain significant brain rewiring requires that you induce a sense of “urgency” that leads to the release of norepinephrine. This hormone, however, will make you feel “agitated,” like you need to get up and go do something. It’s here that you must apply intense focus to fight that urge, ultimately leading to the release of acetylcholine, the neurotransmitter that in combination with the norepinephrine can induce brain growth.