Speech Motor Control

In order to guide development of analysis options within AAA and to gain a fundamental understanding of the neurophysiological basis for speech production, we have conducted research into motor control in general with implications for speech motor control.

Most models of motor control assume a continuous signal descending from the motor cortex. This signal is considred necessary for control of movement trajectory.  Our research shows that cortical control can be pulsatile / ballistic  where the fine management of trajectories is controlled by motoneurons, inhibitory interneurons and renshaw cells in the relevant motor nucleus or spinal region. 

Pulsatile movement control (PMC2019 conference)

A pulse-step model of speech motor control (ISSP2024 conference)

It should be noted that since these publications, the equilibrium hypothesis has been discarded. There is evidence that Renshaw cells form part of a motor nucleus circuit that mirrors the proprioceptive feedback circuit but with no transmission delay. That circuit learns via the cerebellum, the expected proprioceptive feedback and forms a predictive control signal that drives the movement. If proprioceptive signals are received (after transmission lag) that differ from this prediction then they form an error correction signal which may be applied in the second half of the movement i.e. as part of the pulse correcting the target landing position.