This study investigates how belief and expectation influence empathic pain-the pain we feel when observing others in distress. Healthy adult participants will be randomly assigned to one of three groups: no-treatment control, placebo nasal spray, oxytocin-containing nasal spray. Participants in both the placebo and oxytocin conditions will be informed that they are receiving oxytocin, described as a potent agent for pain relief. During functional MRI scanning, all participants will view naturalistic pain-related videos and provide ratings of perceived subjective pain. The study aims to examine how cognitive beliefs and neuromodulatory interventions alter subjective pain experience and brain activity, including changes in brain network communication.

This study examines how belief-driven expectations modulate empathic pain at both behavioral and neural levels. Healthy adult participants will be randomly assigned to one of three groups: no-treatment control, placebo nasal spray, oxytocin-containing nasal spray. Participants in both the placebo and oxytocin conditions will be informed that they are receiving oxytocin, described as a potent agent for pain relief.

During fMRI scanning, participants will complete a naturalistic empathic pain task by viewing videos depicting others in pain and rating their perceived pain on a standardized scale. Behavioral data will be transformed into analgesia-weighted scores to capture individual sensitivity to expectation-driven analgesia. Neural data will include whole-brain voxel-wise activity, multivariate predictive patterns derived from partial least squares regression (PLSR), and directed functional connectivity assessed using lagged partial-correlation directionality analysis (LPC-DA) to evaluate top-down and bottom-up information flow.

The primary objectives are to (1) assess the behavioral effects of expectation-driven analgesia, (2) identify brain regions predictive of pain modulation, and (3) characterize hierarchical network reorganization under different interventions.

Inclusion Criteria:

• (1) Healthy subjects without any past or present psychiatric or neurological disorders; (2) Healthy subjects without any current psychotherapeutic medication.

Exclusion Criteria:

• (1) Participant with any past or present psychiatric or neurological disorders; (2)Participant with any current psychotherapeutic medication.

Eligibility is based on biological sex. Both male and female participants are eligible. Female participants must confirm that they are not pregnant, not using hormonal contraceptives, and not menstruating during the study period.

The placebo (PLC) and oxytocin (OXT) spray conditions were conducted under a single-blind design due to all participants in both the placebo and oxytocin conditions will be informed that they are receiving oxytocin, described as a potent agent for pain relief.