An edited version of my Friday Evening Discouse given to the Royal Institution on 11 April 2008. Abstract: The vagus nerves (cranial nerve X) connects our brainstem to the body, facilitating monitoring and control of many automatic functions; the vagus electrically links our gut, lungs and heart to the base of the brain in an evolutionarily-ancient circuit, similar between mammals and also seen in birds, reptiles, and amphibians. The vagus comprises a major part of the parasympathetic autonomic nervous system, contributing to the motor control of important physiological functions such as heart rate and gut motility. The vagus is also sensory, relaying protective visceral information leading to reflexes like cough and indication of lung volume. The vagus has been described as a neural component of the immune reflex. By monitoring changes in the level of control exerted by the vagus, apparent as beat by beat changes of heart rate, it is possible to indirectly view the effect of pharmaceuticals and disease on brainstem function and neural processes underlying consciousness. The paired vagus nerves of humans have different functions, and stimulation of the left vagus has been shown to be a therapeutic treatment for epilepsy, and may modulate the perception of pain.
about 11 years ago