During speech production, we make vocal tract movements with remarkable precision and speed.
Starting with the earliest cortical stimulation studies, we have learned much about what brain regions
are involved with speech motor control. However, our understanding of how activity in these regions
gives rise to the movements made is limited, in part due to the challenge of simultaneously acquiring
high-resolution neural recordings and detailed vocal tract measurements. A complete neurobiological
understanding of speech motor control requires determination of the relationship between simultaneously
recorded neural activity and the kinematics of the speech articulators (i.e, lips, jaw, and tongue).
Recent advances in human electrophysiological recordings allow us to observe neural activity in these
regions with unprecedented resolution, but without concurrently measuring the speech articulators it
is difficult to interpret this activity. To overcome this challenge, we combined ultrasound and video
monitoring of the supralaryngeal articulators (lips, jaw and tongue) with electrocorticographic (ECoG)
recordings from the cortical surface to investigate how neural activity relates to measured articulator
movement kinematics (position, speed, velocity, acceleration) during the production of English vowels.
In this document, we first provide a review of the functional organization of primary speech motor
cortex, also called ventral sensory motor cortex (vSMC). Next, we describe and validate methods for
a noninvasive, multi-modal imaging system to monitor vocal tract kinematics that is compatible with
bedside human neurophysiological recordings. Last, we use these methods to examine the relationship
between activity in vSMC and the kinematics of speech articulator movements. These findings
demonstrate novel insights into how articulatory kinematic parameters are encoded in vSMC during
speech production.
