Sensorimotor Response to Tongue Displacement Imagery by Talkers with Parkinson’s Disease

Abstract

In a previous study, we asked healthy adult speakers to produce the word head under noise-masked (visual only) conditions and while watching videos of a 3D tongue avatar that gradually morphed from producing head to had. Results indicated that during the visual mismatch phases all participants entrained to the visually presented word, head, without being aware that their vowel quality had changed. Here, we explore whether similar effects occur for individuals with presumed sensorineural processing disorders, patients with Parkinson's disease (PD). We also examine the effects of PD treatment on this entrainment behavior. Participants were 14 individuals with PD, with eight in ongoing speech/language therapy, and six reporting no recent therapy. Participants heard pink noise over headphones and produced the word head under four viewing conditions: First, while viewing repetitions of head (baseline); next, during "morphed" videos shifting gradually from head to had (ramp); then videos of had (maximum hold); and finally videos of head (after effects). Analysis with a linear mixedeffects model indicated a significant F1 difference between baseline and maximum hold phases for the productions of the treated PD group, but not for the untreated group. Implications for the causes and treatment of PD speech disorders are discussed.