Distinct neural circuits processing pleasant and unpleasant sounds: an fMRI-based approach.

backgroundInvestigating how the human brain processes the emotional valance of sounds is critical for understanding sensory, emotional, and motor integration at the neurobiological level. The current study utilized functional magnetic resonance imaging (fMRI) to investigate the differential brain activation patterns elicited by pleasant, unpleasant, and neutral sounds from the International Affective Digital Sounds (IADS-2) collection. Thirty healthy volunteers listened to these sounds under fMRI, followed by post-scan ratings of valence (pleasant versus unpleasant) and arousal (calm versus exciting).

resultsAverage ratings did not differ from IADS-2 norms. Pleasant sounds significantly activated brain regions implicated in reward and positive affect, including the mPFC, ventral anterior cingulate cortex, and inferior frontal gyrus, compared to neutral sounds. Alternatively, unpleasant sounds elicited stronger and more widespread activation, particularly in the amygdala, nucleus accumbens, insula, and cerebellum, regions associated with negative affect and aversive learning.

conclusionThese results demonstrate the pivotal contributions of the amygdala in identifying unpleasant stimuli and of the mPFC in assessing pleasant auditory inputs, expand our current understanding of affective regulation at the neural circuit level, and provide a foundation for the development of sound-based interventions to treat auditory-emotional disorders such as misophonia and anxiety. CLINICAL TRIAL NUMBER: Not applicable.