Mapping Human Laryngeal Motor Cortex during Vocalization.
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ABSTRACT:
SUBMITTER: Eichert N
PROVIDER: S-EPMC7610685 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Speech perception is believed to recruit the left motor cortex. However, the exact role of the laryngeal subregion and its right counterpart in speech perception, as well as their temporal patterns of involvement remain unclear. To address these questions, we conducted a hypothesis-driven study, utilizing transcranial magnetic stimulation on the left or right dorsal laryngeal motor cortex (dLMC) when participants performed perceptual decision on Mandarin lexical tone or consonant (voicing contrast) presented with or without noise. We used psychometric function and hierarchical drift-diffusion model to disentangle perceptual sensitivity and dynamic decision-making parameters. Results showed that bilateral dLMCs were engaged with effector specificity, and this engagement was left-lateralized with right upregulation in noise. Furthermore, the dLMC contributed to various decision stages depending on the hemisphere and task difficulty. These findings substantially advance our understanding of the hemispherical lateralization and temporal dynamics of bilateral dLMC in sensorimotor integration during speech perceptual decision-making.
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Project description:OBJECTIVE:Spasmodic dysphonia (SD) is a debilitating voice/speech disorder without an effective cure. To obtain a better understanding of the underlying cortical neural mechanism of the disease we analyzed electroencephalographic (EEG) signals of people with SD during voice production. METHOD:Ten SD individuals and 10 healthy volunteers produced 50 vowel vocalization epochs of 2500 ms duration. Two EEG features were derived: (1) event-related change in spectral power during vocalization relative to rest, (2) inter-regional spectral coherence. RESULTS:During early vocalization (500-1000 ms) the SD group showed significantly larger alpha band spectral power over the left motor cortex. During late vocalization (1000-2500 ms) SD patients showed a significantly larger gamma band coherence between left somatosensory and premotor cortical areas. CONCLUSIONS:Two atypical patterns of cortical activity characterize the pathophysiology of spasmodic dysphonia during voice production: (1) a reduced movement-related desynchronization of motor cortical networks, (2) an excessively large synchronization between left somatosensory and premotor cortical areas. SIGNIFICANCE:The pathophysiology of SD is characterized by an abnormally high synchronous activity within and across cortical neural networks involved in voice production that is mainly lateralized in the left hemisphere.
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