Imaging sensorimotor interactions during speech communication

Spoken language is a powerful communication tool, which is unique to humans. Growing evidence shows that both motor and sensory systems in the human brain are engaged in speech production and perception. Fluent speaking involves coordination of precise movements of articulatory organs and monitoring of both somatosensory and auditory consequences of these movements. Speech comprehension, on the other hand, involves auditory analysis of acoustic speech signals and mapping these signals onto motor articulatory gestures. Viewing a talker‘s speech gestures (i.e., lipreading) is an important component of natural face-to-face communication, which engages the motor system and multiple sensory (visual, auditory, and somatosensory) systems. How interactions between motor and sensory systems support fluent speaking and efficient analysis of acoustic and visual speech signals is still poorly understood. The present research project will address these fundamental questions by using a novel method, which combines brain stimulation and imaging. We will use transcranial magnetic stimulation (TMS) to disrupt the regions in the motor cortex that control movements of articulators and functional MRI (fMRI) and magnetoencephalography (MEG) to measure the consequences of these motor disruptions on processing of sensory signals. This method will reveal whether sensory systems are functionally connected with the motor system during processing of speech signals. The project also uses fMRI to examine functional connectivity between motor and sensory systems during speech communication in fluent speakers and in people who stutter. We aim to determine whether in stuttering speakers functional coupling between the motor and sensory systems during speech perception and production is abnormal. We will also examine the effects of TMS-induced motor disruption on the sensorimotor mechanisms supporting fluency of speech. Delayed auditory feedback (DAF) reduces fluency in normal speakers, but improves it in people who stutter. We will test whether a new promising brain stimulation method (direct current stimulation, DCS) could prolong the effects of DAF on fluency in people who stutter. In sum, the research project is expected to provide new knowledge on the interregional connections that support speech perception and production in the healthy brain and in the brain of people who stutter. The findings will lead to better understanding of the neural basis of speech communication and possibly to development of better treatments for speech and language problems.

Spoken language is a powerful communication tool, which is unique to humans. Growing evidence shows that both motor and sensory systems in the human brain are engaged in speech production and perception. Fluent speaking involves coordination of precise movements of articulatory organs and monitoring of both somatosensory and auditory consequences of these movements. Speech comprehension, on the other hand, involves auditory analysis of acoustic speech signals and mapping these signals onto motor articulatory gestures. Viewing a talker‘s speech gestures (i.e., lipreading) is an important component of natural face-to-face communication, which engages the motor system and multiple sensory (visual, auditory, and somatosensory) systems. How interactions between motor and sensory systems support fluent speaking and efficient analysis of acoustic and visual speech signals is still poorly understood. The present research project will address these fundamental questions by using a novel method, which combines brain stimulation and imaging. We will use transcranial magnetic stimulation (TMS) to disrupt the regions in the motor cortex that control movements of articulators and functional MRI (fMRI) and magnetoencephalography (MEG) to measure the consequences of these motor disruptions on processing of sensory signals. This method will reveal whether sensory systems are functionally connected with the motor system during processing of speech signals. The project also uses fMRI to examine functional connectivity between motor and sensory systems during speech communication in fluent speakers and in people who stutter. We aim to determine whether in stuttering speakers functional coupling between the motor and sensory systems during speech perception and production is abnormal. We will also examine the effects of TMS-induced motor disruption on the sensorimotor mechanisms supporting fluency of speech. Delayed auditory feedback (DAF) reduces fluency in normal speakers, but improves it in people who stutter. We will test whether a new promising brain stimulation method (direct current stimulation, DCS) could prolong the effects of DAF on fluency in people who stutter. In sum, the research project is expected to provide new knowledge on the interregional connections that support speech perception and production in the healthy brain and in the brain of people who stutter. The findings will lead to better understanding of the neural basis of speech communication and possibly to development of better treatments for speech and language problems.