PNAs: revealing altruistic behavior to relieve physiological pain

On December 30, 2019, Proceedings of the National Academy of Sciences of the United States of America (PNAs) online published the paper "authentic behaviors related physical pain" by Professor Xie Xiaofei, School of psychology and cognitive science, Peking University This study found that altruistic behavior can alleviate the physiological pain of helpers, and initially revealed the neural mechanism of this effect Helping others is often accompanied by the consumption of self resources, but it can improve the health and happiness of the helpers Why does this seemingly contradictory phenomenon happen? The understanding of this problem is becoming more and more important in life and death situations Intuitively speaking, altruism is not an adaptive choice Individuals can maximize their own interests by storing and retaining resources However, facts show that altruism often occurs when crises break out What is the effect of altruistic behavior on the physiological and psychological process of the helpers? This study suggests that altruistic behavior may affect the feelings of the helpers to unpleasant stimuli (such as physical pain) One possibility is that altruistic behavior can enhance pain experience, because altruistic behavior means one-way payment of time, energy, money and other resources, and the tangible loss is painful and disgusting; however, the other possibility is that altruistic behavior can bring shapeless benefits through enhancing psychological process, which plays a buffering role in helping people's physical pain This study supports the latter hypothesis In the field study of Ya'an earthquake, the researchers observed that altruistic behavior alleviated pain in blood donors, and the degree of subjective pain in blood donation was significantly lower than that in physical examination Later, the researchers found that the subjects who volunteered altruism (to revise a reading material for migrant children free) reported lower pain levels in the cold pressure pain paradigm than those who did not know that the purpose of revising the reading material was to help others, and persisted in the ice water for a longer time In the next experimental study, the tourniquet paradigm was used to simulate the pain caused by ischemia The subjects completed two tourniquet tests and were asked to fill in a questionnaire during the break Half of the randomly assigned subjects learned that they had won 10 yuan for the earthquake disaster area by filling in the questionnaire, and put the money into the donation box (altruistic group); the other half learned that they had earned 10 yuan extra reward for themselves (control group) That is to say, all the subjects' behaviors are exactly the same, and the difference lies only in the meaning of the behaviors The results showed that the level of pain felt in the second tourniquet test in the Rita group was significantly lower than that in the control group, indicating that donating money to the disaster area had a alleviating effect on the pain (Figure 1) This study further explored the neural mechanism of pain relief by Rita The subjects were told to carry out two unrelated experiments in MRI In each trial, first make a altruistic or control choice, and then receive an electric shock of different strength on the back of the right hand, and report the degree of pain by pressing the key Altruistic choice is to decide whether to pay some costs for orphans to win higher donations, and control choice is to judge whether the nature of the two lines of graphics is consistent The results showed that, compared with control selection, the neural activity of ventromedial prefrontal cortex (vmPFC) was significantly increased, while the activity of brain areas related to pain processing (such as anterior cingulate cortex and bilateral insula) was significantly decreased, which confirmed the decrease of pain from the level of neural activity VmPFC is closely related to the experience of sense of meaning The activation degree of vmPFC plays an intermediary role in the relationship between altruistic behavior and the activation degree of pain brain area, which indicates that the sense of meaning obtained from altruistic behavior plays a role in relieving pain (Figure 2-4) In a hospital in Hebei Province, the researchers selected patients with lung cancer more than 4 stages for a week of intervention: the cancer patients in the experimental group cleaned the public areas for their patients every day, participated in a meal nutrition sharing meeting, and carefully prepared recipes for their patients; the patients in the control group cleaned themselves every day, and participated in a theme lecture on meal nutrition Although there was no difference in the initial pain level between the altruistic group and the control group, the degree of pain reduction in the altruistic group was significantly greater than that in the control group with individual and group activities This study improves the understanding of human altruistic behavior, reveals that altruistic behavior can help people get immediate benefits, help individuals to cope with threatened situations, and provide a low-cost and no side effects way of thinking for pain management