Unravelling the role of the opioid system in pain empathy

This project investigates the neural bases of empathy, the ability to understand and re- experience the emotions of others. According to contemporary accounts of empathy, the same brain regions are active during both the empathic and direct experience of an emotion. In the special case of empathy for pain, previous research also demonstrated a key role of the bodys own opioid system. However, previous studies in this research area have left some key questions unanswered, which we intend to clarify by employing a novel experimental approach. Thereby, we want to take the understanding of the neural bases of empathy to the next level. We will apply two types of pharmacological manipulations of the bodys opioid system in two experiments with human participants: we will administer both opioids and pharmacological compounds that inhibit the action of the bodys own opioids. This will result in opposite effects on the opioid system in the two experiments. After administration of these drugs, participants` responses to self-perceived and empathic pain will be measured using functional magnetic resonance imaging. Using different state-of-the-art methods of analysis, we will be able to precisely investigate and describe the similarity of neuronal processes during self-perceived and empathic pain. The combination of our experimental approach with a range of analytical techniques and the measurement of drug effects on the interactions of different brain regions shall significantly advance the understanding of the role of the opioid system in empathy for pain. Apart from the relevance for basic research in the field of social neuroscience, our project could also make an important contribution to an increasingly relevant topic: understanding the impact of opiates on empathy and our social interactions seems to be highly important in light of the prescription opiate crisis in the United States.

This research project explored the role of the opioid system in a wide range of socio-cognitive functions and prosocial behavior. Several experiments were conducted to deepen our understanding of this neurotransmitter system and the theory of "shared representations." This theory posits that during the empathic experience of emotions, the same brain areas are activated as during the direct experience of the corresponding emotions. To address the research questions, behavioral experiments and imaging studies using functional magnetic resonance imaging (fMRI) were carried out, systematically manipulating the opioid system through pharmacological interventions. In experiments where the opioid system was stimulated, both the perception of one's own pain and the processing of unpleasant tactile stimuli were reduced, as was the empathic perception of these stimuli in others. Conversely, suppression of the opioid system using receptor blockers impaired the recognition of pain-expressive facial expressions and empathy for pain, but had no effect on the processing of tactile stimuli. Another experiment demonstrated that the opioid system also plays a role in regulating prosocial behavior aimed at preventing painful stimuli. These findings raised further questions about the impact of pain medication on empathy and social interactions, which we addressed through an initial questionnaire study. This study revealed that increased use of pain medication was associated with lower levels of empathy and prosocial helping behavior. Further investigations within this project examined altered connectivity between brain regions, such as the hippocampus, during the perception of empathic pain. We also analyzed personality traits and neural characteristics that promote or hinder responsiveness to placebo analgesia. Finally, by embedding our findings into the broader scientific context of our field, we formulated a theory on how empathy for specific emotions is represented across different processing levels and how it impacts social behavior. These levels may serve as predictors for potential impairments in clinical conditions associated with pain. Additional experiments, building on the findings gained during the project and initiated within the project timeframe, will soon provide further insight regarding the role of the opioid system in an even broader range of socio-cognitive functions. They will also shed light on the interplay between acute and chronic pain and the underlying neural mechanisms. The insights gained from this project significantly expand our understanding of the role of the opioid system in interpersonal contexts. While previous research primarily focused on empathy for pain, we demonstrated effects on other domains of social cognition as well as on interpersonal prosocial behavior. We anticipate that the research questions and findings from this project will inspire further studies, providing new insights into the opioid system, its effects on social cognition and prosocial behavior, and contributing to a deeper understanding of shared representations in social cognition.