Excellent diagram, Susan. No doubt the pathway and reaction will be different for us all. FWIW, in researching choline supplementation, I find many references to it's stimulant-like properties, such as this one, but appreciate your more detailed explanation and understand effects are likely individualized.
This supplement has also been shown to increase the density of dopamine receptor neurons which may lead to mood enhancing benefits. CDP Choline even has a stimulant-like effect and has been used successfully by people with ADD and ADHD.