Abstract
Structural adaptations of the corpus callosum have been well documented in early-trained instrumental musicians, reflecting experience-dependent plasticity in response to bimanual coordination and auditory–motor integration. Although the sensorimotor demands of singing differ, professional vocal training also requires precise control of bilateral vocal tract musculature and integration of auditory feedback; yet, less is known about whether similar adaptations occur in professional singers. This study used structural neuroimaging to investigate variations in callosal thickness in relation to vocal training in 55 participants, including 27 professionally trained opera singers and 28 non-singers. A significant negative correlation between age at first singing lesson and callosal thickness was observed in singers, with effects surviving correction for multiple comparisons in the anterior third (rostrum, genu, rostral body), at the anterior-posterior midbody border, and the isthmus. While group comparisons revealed greater callosal thickness in singers than non-singers in these same regions, these differences did not remain significant after correction. Likewise, a positive correlation between years of professional singing and callosal thickness in the midbody did not survive correction for multiple comparisons. Our main finding aligns with prior evidence of training-related plasticity in the corpus callosum and suggests that early musical experience—including in the context of intensive vocal practice—may contribute to enhanced interhemispheric connectivity. Although the current design does not allow us to isolate effects specific to singing compared to other forms of sensorimotor training, the results underscore developmental timing as a key factor in how prolonged musical experience may shape brain structure.