The brain’s processing of emotions related to prolonged pain and pleasure has been uncovered by researchers. A team of researchers, led by LEE Soo Ahn and WOO Choong-Wan at the Center for Neuroscience Imaging Research (CNIR) within the Institute for Basic Science (IBS), in collaboration with CHOI Myunghwan at Seoul National University and Tor D. WAGER at Dartmouth College, used functional Magnetic Resonance Imaging (fMRI) to record brain activity while participants experienced sustained pain and pleasure.
Research has identified brain activity patterns associated with the experience of pain and pleasure, including the effects of capsaicin and chocolate. Using advanced machine learning techniques, scientists have been able to uncover these patterns and their relationship to sustained pain and pleasure.
Pain and pleasure, despite being opposites, are closely linked. Previous research has pointed to specific brain regions that respond to both sensations. However, most of these studies have been carried out on animals rather than humans, and there is still a lack of research directly comparing the brain’s response to pain and pleasure in the same individuals.
The research team conducted an experiment to induce sustained pain and pleasure in participants using capsaicin and chocolate fluids in an MR scanner. The participants reported moment-to-moment changes in their subjective feelings of pleasantness and unpleasantness while experiencing sustained pain and pleasure. The participants’ reports showed a gradual increase in pleasantness and unpleasantness during the delivery of capsaicin and chocolate fluids, which then decreased after the deliveries ended. The team’s goal was to identify the brain regions activated by these dynamic changes in sustained pain and pleasure.
The article states that a research team conducted an experiment where they gathered brain imaging data and real-time ratings of pleasantness or unpleasantness from 58 participants. The team used machine learning techniques to analyze the brain data and found a group of brain regions that responded to both sustained pain and pleasure. Based on the brain activity patterns of these common brain regions, the team created two predictive models to measure (1) the strength of emotional experiences regardless of their pleasantness or unpleasantness (referred to as ‘affective intensity’) and (2) the degree of pleasantness or unpleasantness (referred to as ‘affective value’).”We have discovered that these models were able to accurately predict the emotional intensity and valence associated with long-lasting feelings of pleasure and pain. This was true for both the original 58 individuals used for training and an additional 61 individuals in a separate test group. The patterns of brain activity that were able to forecast emotional intensity and valence were different from each other and linked to specific functional brain networks. This indicates that the emotional intensity and valence represent various aspects of the brain’s mechanisms related to the interaction between pain and pleasure. Although previous studies have focused on these areas separately, our research brings them together.Dr. WOO Choong-Wan, associate director of IBS, led a study on the experiences of pain and pleasure in the same individuals. He mentioned that there has been little research comparing the two. Dr. WOO believes that understanding the brain activity patterns for affective valence and intensity can help us understand how pain and pleasure interact, as well as the brain mechanisms underlying depression in chronic pain patients.
The first author of the study, LEE Soo Ahn, emphasized that the results show that pain and pleasure share the same emotional information on pleasantness.and discomfort,” he also stated, “It’s important to recognize that emotional feelings and their strength can be processed in various areas of the brain.”
