Feedback and feedforward control of intonation in cerebellar ataxia

Cerebellar ataxia impairs motor control for speech, impacting the coordination of feedback and feedforward mechanisms essential for accurate intonation. This study investigates the response to perturbed pitch auditory feedback in 22 individuals with cerebellar ataxia and 29 control participants to examine how cerebellar damage affects feedforward and feedback control mechanisms of utterance-level pitch. Participants completed sustained vowel and sentence-production tasks, including sentences varying by semantic focus, while their auditory feedback was perturbed by ±200 cents. The results revealed that participants with ataxia exhibited larger responses compared to controls across both tasks, indicating compromised feedback control. However, participants with ataxia retained the ability to modulate their responses based on the speech task and semantic focus, suggesting that task-dependent feedforward mechanisms remain relatively intact. Unlike prior research on feedforward control for speech in cerebellar ataxia, these findings highlight the preservation of a higher-level feedforward control system for dynamic pitch modulation during speech.