Neural representations of enhanced speech motor control in trained singers

Abstract

Humans are unrivalled amongst the great apes in our capacity for vocal learning, which forms a key component our facility for articulate speech. Here, we used a speech imitation task to investigate the neural representation of the human larynx, which has a distinct cortical topography and innervation in humans that may underpin our sophisticated vocal capabilities compared with non-human primates. In an MRI study, 25 highly trained singers and 24 non-singing control participants adjusted voice pitch (F0) and vocal tract length (VTL) to mimic altered auditory targets generated from recordings of their own speech. Participants simultaneously underwent real-time anatomical scans of the vocal tract and functional scans of brain activity. Representational similarity analyses of neural activation data identified representation of the two vocal parameters in regions of somatomotor cortex previously associated with laryngeal control. Singers showed more accurate task-relevant larynx height modulation (as measured with vocal tract MRI) when imitating VTL, which was underpinned by stronger representation of VTL within a region of right dorsal somatomotor cortex previously related to singing experience. Our findings offer the first behaviourally validated, representational account of speech imitation within larynx somatomotor cortex, suggesting that the behavioral and neural correlates of singing expertise extend to human speech.