Modulation of event-related potentials associated with orofacial skin stretch during speech production

Takayuki Ito (1, 2) , Hiroki L Ohashi (2) , Eva L Montas (2) , Vincent Gracco (3, 2)

1 GIPSA-PCMD - GIPSA - Perception, Contrôle, Multimodalité et Dynamiques de la parole
2 Haskins Laboratories
3 School of Communication Sciences and Disorders

Modulation of sensory event-related potentials occurs before or during voluntary movement. For speech, the amplitude of auditory cortical potentials is reduced during speech production, the so-called speech induced suppression. However, it is unknown whether somatosensory processing is also suppressed during speech production. The current study addressed this question by examining whether somatosensory event-related potentials (ERPs) associated with facial skin deformation are changed during speech production tasks. We investigated changes in the magnitude of somatosensory ERPs during speech posture with and without voicing, and also with changes associated with different speech utterances. ERPs from 64 scalp sites in response to somatosensory stimulation associated with facial skin stretch were recorded. Participants engaged in: 1) a vowel production task, and, 2) a non-speech task in which participants maintain the same posture without voicing. Three vowels (/a/, /i/, and /u/) were used in these two production tasks. Somatosensory ERPs in the six task conditions (3 vowels x 2 production tasks) were compared with the ERPs from control (resting) condition. We applied global field power (GFP) measures to evaluate the amount of activity of each time point for the ERPs on the cortical surface. GFP showed two peaks consistently around 160 ms and 320 ms after somatosensory onset in all conditions. The first peak amplitude was significantly different for the three vowel tasks, but there were no significant changes in the second peak. The first peak in the vowel /u/ was reliably smaller than those in the other two vowels. This was found consistently in both vowel production and posture tasks. Cluster analysis of the temporal pattern of the GFP showed a significant reduction of somatosensory GFP in the /u/ condition relative to the control condition, while the other two vowel conditions were not reliably different. Displacement of facial skin stretch was not different across the three vowel tasks, indicating that the changes of ERP responses were not attributed to a magnitude of the facial skin deformation. Taken together, the sensitivity of somatosensory ERP associated with facial skin deformation changes according to the specific vowel being produced. More importantly, there is evidence for a short latency (around 160 ms) suppression of somatosensory input during speech. It appears that sensory suppression mechanisms are reflected in both sensory modalities (auditory and somatosensory) associated with speech production and the somatosensory system may be modulated differently relative to phonetic identity.

Mots clés: Sensory suppression; Event-related potentials; Somatosensory processing; Speech production perturbation

Domaines: Neurosciences; Linguistique

Takayuki Ito, Hiroki L Ohashi, Eva L Montas, Vincent Gracco. Modulation of event-related potentials associated with orofacial skin stretch during speech production. Neuroscience 2017 - Annual meeting of the Society for Neuroscience, Nov 2017, Washington, DC, United States. ⟨hal-01651654⟩