Human larynx motor cortices coordinate respiration for vocal-motor control

Michel Belyk, Rachel Brown, Deryk S Beal, Alard Roebroeck, Carolyn McGettigan, Stella Guldner, Sonja A Kotz*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Vocal flexibility is a hallmark of the human species, most particularly the capacity to speak and sing. This ability is supported in part by the evolution of a direct neural pathway linking the motor cortex to the brainstem nucleus that controls the larynx the primary sound source for communication. Early brain imaging studies demonstrated that larynx motor cortex at the dorsal end of the orofacial division of motor cortex (dLMC) integrated laryngeal and respiratory control, thereby coordinating two major muscular systems that are necessary for vocalization. Neurosurgical studies have since demonstrated the existence of a second larynx motor area at the ventral extent of the orofacial motor division (vLMC) of motor cortex. The vLMC has been presumed to be less relevant to speech motor control, but its functional role remains unknown. We employed a novel ultra-high field (7T) magnetic resonance imaging paradigm that combined singing and whistling simple melodies to localise the larynx motor cortices and test their involvement in respiratory motor control. Surprisingly, whistling activated both 'larynx areas' more strongly than singing despite the reduced involvement of the larynx during whistling. We provide further evidence for the existence of two larynx motor areas in the human brain, and the first evidence that laryngeal-respiratory integration is a shared property of both larynx motor areas. We outline explicit predictions about the descending motor pathways that give these cortical areas access to both the laryngeal and respiratory systems and discuss the implications for the evolution of speech.

Original languageEnglish
Article number118326
Number of pages10
JournalNeuroimage
Volume239
Early online date30 Jun 2021
DOIs
Publication statusPublished - 1 Oct 2021

Keywords

  • FMRI
  • FUNCTIONAL NEUROANATOMY
  • LOWER BRAIN-STEM
  • Larynx
  • MONOSYNAPTIC PROJECTIONS
  • Motor cortex
  • NEURAL PATHWAYS
  • NUCLEUS RETROAMBIGUUS
  • PHONATION
  • PITCH
  • Respiration
  • SENSORIMOTOR CORTEX
  • Song
  • VOCALIZATION
  • Voice
  • Whistle
  • fMRI

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