On February 18, King’s College Hospital in London announced that a grade II glioma patient was playing the violin while the surgeons removed the tumor from her brain. This surprising procedure is made possible by the fact that the brain does not have pain receptors. Which does not necessarily mean that he feels none.
The brain has no nociceptors – the nerves that detect damage (or threat of damage) to our body and that signal the situation to our spinal cord and our brain. As a result, the belief that the latter does not feel any pain has taken shape, until entering popular culture.
In the movie Hannibal from 2001, a particularly disgusting scene depicts the eponymous serial killer cutting the brain of a perfectly conscious, although drugged, FBI agent. “You see, the brain itself does not feel any pain”Hannibal Lecter explains to a horrified Clarice Starling.
But if the brain doesn’t feel any pain, what causes the headache?
Although the brain does not have nociceptors, many other structures inside our head have them, including blood vessels, muscles and nerves in the neck, face, and scalp. These are the problems faced by these structures that cause headaches.
The pain when eating ice cream seems to be caused by sudden changes in blood flow in the veins between the back of the throat and the brain. Dehydration, on the other hand, causes headache by irritating the blood vessels in the head. This is one of the reasons for the throbbing headaches of the aftermath of a little too alcoholic holidays … And any dentist will tell you that the headache may be the sign that you are overworking your jaws, perhaps because that you cringe while you sleep.
The origin of the pain felt during a migraine is not yet well understood, but it is believed to result from the activation of nociceptors located in the meninges – the membranes that surround the brain and spinal cord like cellophane. . The cause of this activation is not yet clear, however.
Even if the brain has no nociceptors, a headache can be a sign that it is having a problem. Prolonged pain that does not respond to medication or that is sudden and extraordinarily severe may be signs of a serious brain abnormality, such as a tumor, hemorrhage, or infection. The pain caused by these problems is not generated by the activation of nociceptors located in the brain itself (there are none); they result from the pressure that the brain, by swelling, exerts on the other structures of the head.
More than just a sensory experience
Basically, Hannibal Lecter was wrong that the brain does not feel pain. Even if he does not have nociceptors, he smells all our pain. The brain is indeed the organ through which we interpret, evaluate and experience all the sensory signals of our body.
Scientists distinguish between the nociception – the nerve signal corresponding to the damage caused to our body – and the pain, the unpleasant emotional and cognitive experience that normally occurs when our nociceptors are activated.
This means that pain is more than just a sensory experience, it is influenced by our thoughts, feelings and social relationships. For example, how we feel pain is affected by what we think: what we believe pain can mean, what we remember from previous pain experiences.
Pain is also an emotional experience: people with depression report experiencing more pain in their daily lives. And inducing a drop in morale in people otherwise not prone to depression increases their feelings of pain and decreases their tolerance towards it.
Pain is also a social experience. During an experiment, students were asked to hold their hands as long as possible in painfully cold water. They were able to tolerate pain for a longer time when they thought the experimenter was one of their teachers (if they thought the experimenter was another student, they tolerated it less). This result shows that when we are asked about our pain, the identity of the person asking the question is important.
The changes brought about by social influences on pain also underline the benefits that can be obtained from the support of people who love us. In another study using the same ice bucket method, participants showed greater tolerance for cold pain when someone else observed the experience in silence (compared to the situation where they were alone with the experimenter). And if the observer was a friend of the same sex, the participants’ tolerance increased, even if that friend was not present in the room (but very close).
The perception of pain is influenced, and there are many. It is therefore not surprising that it is so complex and frustrating to relieve it. The good news is that each of these influences also represents a way to manage pain. Helping people change their way of thinking, their feelings about their pain is an important point in its management, as well as the maintenance of their social relationships.
This article is republished from The Conversation under a Creative Commons license. Read the original article.