Singing training predicts increased insula connectivity with speech and respiratory sensorimotor areas at rest

The insula contributes to the detection of salient events during goal-directed behavior and participates in the coordination of motor, multisensory, and cognitive systems. Recent task-fMRI studies with trained singers suggest that singing experience can enhance the access to these resources. However, the long-term effects of vocal training on insula based networks are still unknown. In this study, we employed resting-state fMRI to assess experience-dependent differences in insula co-activation patterns between conservatory-trained singers and non-singers. Results indicate enhanced bilateral insula connectivity in singers relative to non-singers with constituents of the speech sensorimotor network in both hemispheres. Specifically, with the cerebellum (lobule VI, crus 2), primary somatosensory cortex, the parietal lobes, and the thalamus. Furthermore, singing training predicted enhanced bilateral co-activation of primary sensorimotor areas representing the larynx (with left dorsal anterior insula, dAI) and the diaphragm (with bilateral dAI) - crucial regions for cortico-motor control of complex vocalizations, as well as the thalamus (with bilateral posterior insula/left dAI) and the left putamen (with left dAI). Together, these data support a crucial role of the insula in respiratory and laryngeal control and suggest that singing experience enhances the integration of somatosensory information within the speech motor system, perhaps by strengthening salient associations of bodily signals associated with conscious and non-conscious aspects of expressive language production within a musical framework.