Orofacial Cutaneous Function in Speech Motor Control and Learning

Abstract

Somatosensory signals from facial skin can provide a rich source of sensory input. However, it is unknown yet how cutaneous input works on speech motor control and learning. This chapter introduces a kinesthetic role of orofacial cutaneous afferents in speech processing. We argue for specificity of the orofacial somatosensory system from anatomical and physiological perspectives. The contribution of cutaneous afferents to speech production is evident in neurophysiological and psychophysical findings. Somatosensory modulation associated with facial skin deformation induces a reflex for articulatory motion adjustment in speech production and also an adaptive motion change in speech motor learning. In addition, cutaneous mechanoreceptors are narrowly tuned at the skin lateral to the oral angle. An intriguing function of somatosensory inputs associated with facial skin deformation is to interact with the processing of speech perception. Taken together, orofacial cutaneous afferents play an important role in both speech production and perception.