Once home, I googled autism awareness, bumper sticker, and entered a whole world of autism products. Bumper stickers, of course. But also tee shirts, jewelry, stickers (I am someone with autism), mugs. Eventually, I exited even more perplexed than I entered.
In general, the digestive system is controlled by both nerves and hormones. The nerves that control digestion are in the submucosa layer of the tissue and in between the muscle layers of the walls of the organ.
For example, it controls digestion, respiration, the contractions of the heart and of smooth muscles in blood vessels, and the release, by the endocrine system, of hormones which regulate metabolism and growth. Hormones themselves can influence behaviour by their effects on specific parts of the brain.