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

Abstract

The insula contributes to the detection and integration of salient events during goaldirected behavior and facilitates the interaction between motor, multisensory, and cognitive networks. Task-fMRI studies have suggested that experience with singing can enhance access to these resources. However, the long-term effects of vocal motor training on insula-based networks are currently unknown. In this study, we used restingstate fMRI to explore experience-dependent differences in insula co-activation patterns between conservatory-trained singers and non-singers. We found enhanced insula connectivity in singers compared to non-singers with constituents of the speech sensorimotor network, including the cerebellum (lobule VI, crus 2), primary somatosensory cortex, the parietal lobes, and the thalamus. Moreover, accumulated singing training correlated positively with increased co-activation in bilateral primary sensorimotor cortices in the somatotopic representations of the larynx (left dorsal anterior insula, dAI) and the diaphragm (bilateral dAI)-crucial regions for motorcortical control of complex vocalizations-together with the thalamus (bilateral posterior insula/left dAI) and the left putamen (left dAI). The results of this study support the view that the insula plays a central role in the experience-dependent modulation of sensory integration within the vocal motor system, possibly by optimizing conscious and non-conscious aspects of salience processing associated with singing-related bodily signals.

Singers show enhanced performance and neural representation of vocal imitation

“…Several previous studies have explored the neural correlates of vocal expertise, revealing effects on regional activation and structure, as well as connectivity [34][35][36][53][54][55]. In the current study, we found a significant difference between singers and non-singer controls in the spoken imitation of VTL, and in the neural representation of this vocal parameter.…”

“…Neuroimaging studies have shown that primary somatosensory cortex is engaged by both overt and covert speech production [15] and thus could be implicated in both the planning and execution of laryngeal muscle activity. Evidence from highly-trained singers has identified regions of somatosensory cortex proximal to the dorsal LMC whose local activity [34], resting-state connectivity [35], and structure [36], are associated with singing experience. One interpretation of this finding is that it reflects the heightened control and somatosensory/kinesthetic awareness of vocal musculature that are associated with extensive musical training in voice [37].…”

Singers show enhanced performance and neural representation of vocal imitation.

“…Several previous studies have explored the neural correlates of vocal expertise, revealing effects on regional activation and structure, as well as connectivity [33][34][35][50][51][52]. In this study, we found a significant difference between singers and nonsinger controls in the behavioural imitation of VTL, and the neural representation of this vocal parameter.…”

“…A region of left somatomotor cortex identified in the whole participant group did not correspond topographically to previous reports of the larynx motor cortex (LMC). However, a further direct comparison of singers and controls revealed an expertise-related enhancement of VTL representation in right somatosensory cortex, just posterior to the reported location of the dorsal LMC in humans [16][17][18] and in line with a postcentral site previously linked to singing experience [33][34][35]. We speculate that this dorsal site could represent a larynx sensory cortex that is closely coupled to its corresponding LMC during speech motor control [9]: in line with this, probabilistic diffusion tractography analyses of LMC connectivity have revealed dramatically stronger connectivity with somatosensory and inferior parietal cortices in humans than in macaques [46].…”

“…Neuroimaging studies have shown that primary somatosensory cortex is engaged by both overt and covert speech production [15] and thus could be implicated in both the planning and execution of laryngeal muscle activity. Evidence from highly-trained singers has identified regions of somatosensory cortex proximal to the dorsal LMC whose local activity [33], resting-state connectivity [34], and structure [35], are associated with singing experience. One interpretation of this finding is that it reflects the heightened control and somatosensory/kinesthetic awareness of vocal musculature that are associated with extensive musical training in voice [36].…”