Circuits controlling heartbeat, breathing, and digestion are wired to be highly reliable and are unlikely to change through plasticity.

“However, there are aspects of your nervous system that were designed not to be plastic. They were wired so that plasticity or changes in those circuits is very unlikely. Those circuits include things like, the ones that control your heartbeat, the ones that control your breathing, the ones that control your digestion, And thank goodness that those circuits were set up that way because you want those circuits to be extremely reliable.”