In chapter 3, attention has been concentrated on the interrelationships between the enteric nervous system (ENS) and the sympathetic and parasympathetic systems, which transmit signals to the central nervous system (CNS). While up until now the ENS has been regarded as virtually autonomous—as a “little” or “second” brain which influences the gut locally—the evidence to substantiate this is based on inconclusive premises. The evidence presented in this session challenges this view and demonstrates considerable connection and interplay between the ENS and CNS.

Recent tracer and electrophysiological studies have shown, independently, that vagal efferents ramify extensively into a network of fibres which are in contact with large numbers of enteric neurones in the myenteric plexus of the stomach and proximal small intestine. Vagal afferents …