Cardiac Cycle Phase Modulates Pain Processing During Heartbeat-Enhanced Rubber Hand Illusion

Area of Science:

• Neuroscience
• Psychology
• Pain Research

Background:

• Pain perception is influenced by interoceptive signals, including cardiac rhythm.
• Body ownership illusions (BOI) are modulated by interoceptive signals, but their effect on pain processing is debated.
• It is unclear if cardiac-phase-specific pain modulation is independent of BOI.

Purpose of the Study:

• To investigate the effects of cardiac cycles on pain processing.
• To determine the influence of body ownership illusions (BOI) on pain perception.
• To examine the interaction between cardiac cycle and BOI in modulating pain.

Main Methods:

• A virtual reality rubber hand illusion (VR-RHI) paradigm was used to induce BOI.
• Painful electrical stimuli were delivered during systolic and diastolic cardiac phases.
• Pain perception was assessed via thresholds, intensity/unpleasantness ratings, and somatosensory evoked potentials (SEPs) under BOI and control (object) conditions.

Main Results:

• The diastolic phase significantly reduced pain intensity and unpleasantness compared to the systolic phase.
• Diastolic stimulation also led to reduced somatosensory evoked potential (SEP) amplitudes.
• Neither BOI nor its interaction with the cardiac cycle significantly affected pain measures.

Conclusions:

• Cardiac cycle phase independently modulates pain perception, with the diastolic phase being hypoalgesic.
• Body ownership illusions do not influence cardiac-phase-dependent pain modulation.
• These findings disentangle the roles of interoception and body ownership in pain processing.