The unique model of this story appeared in Quanta Magazine.
It is late at evening. You are alone and wandering empty streets in search of your parked automobile once you hear footsteps creeping up from behind. Your coronary heart kilos, your blood strain skyrockets. Goose bumps seem in your arms, sweat in your palms. Your abdomen knots and your muscle tissue coil, able to dash or battle.
Now think about the identical scene, however with none of the physique’s innate responses to an exterior menace. Would you continue to really feel afraid?
Experiences like this reveal the tight integration between mind and physique in the creation of thoughts—the collage of ideas, perceptions, emotions, and persona distinctive to every of us. The capabilities of the mind alone are astonishing. The supreme organ offers most individuals a vivid sensory notion of the world. It can protect recollections, allow us to study and converse, generate feelings and consciousness. But those that may try to protect their thoughts by importing its information into a pc miss a important level: The physique is crucial to the thoughts.
How is this significant brain-body connection orchestrated? The reply includes the very uncommon vagus nerve. The longest nerve in the physique, it wends its approach from the mind all through the head and trunk, issuing instructions to our organs and receiving sensations from them. Much of the bewildering vary of features it regulates, akin to temper, studying, sexual arousal, and worry, are automated and function with out acutely aware management. These advanced responses interact a constellation of cerebral circuits that hyperlink mind and physique. The vagus nerve is, in a method of considering, the conduit of the thoughts.
Nerves are sometimes named for the particular features they carry out. Optic nerves carry alerts from the eyes to the mind for imaginative and prescient. Auditory nerves conduct acoustic data for listening to. The greatest that early anatomists might do with this nerve, nevertheless, was to name it the “vagus,” from the Latin for “wandering.” The wandering nerve was obvious to the first anatomists, notably Galen, the Greek polymath who lived till round the yr 216. But centuries of examine have been required to know its advanced anatomy and performance. This effort is ongoing: Research on the vagus nerve is at the forefront of neuroscience immediately.
The most vigorous present analysis includes stimulating this nerve with electrical energy to reinforce cognition and reminiscence, and for a smorgasbord of therapies for neurological and psychological problems, together with migraine, tinnitus, weight problems, ache, drug dependancy, and extra. But how might stimulating a single nerve probably have such wide-ranging psychological and cognitive advantages? To perceive this, we should perceive the vagus nerve itself.
The vagus nerve originates from 4 clusters of neurons in the mind’s medulla, the place the brainstem attaches to the spinal twine. Most nerves in our physique department straight from the spinal twine: They are threaded between the vertebrae in our spine in a sequence of lateral bands to hold data into and out of the mind. But not the vagus. The vagus nerve is one of 13 nerves that depart the mind straight by means of particular holes in the cranium. From there it sprouts thickets of branches that attain nearly all over the place in the head and trunk. The vagus additionally radiates from two main clusters of outpost neurons, referred to as ganglia, stationed in important spots in the physique. For instance, a big cluster of vagal neurons clings like a vine to the carotid artery in your neck. Its nerve fibers observe this community of blood vessels all through your physique to achieve important organs, from the coronary heart and lungs to the intestine.