The stomach is the second brain
I just recently read this in a biography about an alcoholic writer, Patricia Hightsmith ( The Talented Mr Ripley and Strangers on a Train). The author was suggesting that Ms. Highsmith's problem with alcohol stemmed from the fact that despite not wanting to drink, her stomach (biochemical rewiring to accommodate alcohol??) prompted the ongoing use of it despite her "first brain's" resolutions on the subject.
I thought this to be an interesting theory.