The “Iso-principle” gateway: Neural-autonomic coupling during the dynamic transition from affective resonance to top-down regulation in music-induced emotion regulation

The Iso principle—starting with music that matches a listener’s current emotional state and gradually transitioning toward a desired one—is widely applied in music therapy, yet its neural and physiological mechanisms remain unclear. This study investigated how emotion-congruent music modulates affective and autonomic responses following romantic breakups. Thirty female participants listened to either an Iso-based (sad–calm–happy) or control (happy–calm–happy) music sequence during simultaneous fMRI and heart rate variability (HRV) recordings. The Iso condition was associated with higher parasympathetic activity during music listening and lower post-intervention autonomic arousal. At the neural level, emotion-congruent music was associated with enhanced auditory-limbic connectivity during the initial phase, and sustained engagement of prefrontal regulatory networks, indexed by pgACC–dlPFC connectivity, across both phases of the Iso sequence. These findings reveal a two-stage mechanism underlying music-based emotion regulation, offering neurophysiological evidence for the therapeutic utility of emotion-congruent music.