Feedback and Feedforward Auditory-Motor Processes for Voice and Articulation in Parkinson's Disease

Abstract

Purpose Unexpected and sustained manipulations of auditory feedback during speech production result in “reflexive” and “adaptive” responses, which can shed light on feedback and feedforward auditory-motor control processes, respectively. Persons with Parkinson's disease (PwPD) have shown aberrant reflexive and adaptive responses, but responses appear to differ for control of vocal and articulatory features. However, these responses have not been examined for both voice and articulation in the same speakers and with respect to auditory acuity and functional speech outcomes (speech intelligibility and naturalness). Method Here, 28 PwPD on their typical dopaminergic medication schedule and 28 age-, sex-, and hearing-matched controls completed tasks yielding reflexive and adaptive responses as well as auditory acuity for both vocal and articulatory features. Results No group differences were found for any measures of auditory-motor control, conflicting with prior findings in PwPD while off medication. Auditory-motor measures were also compared with listener ratings of speech function: first formant frequency acuity was related to speech intelligibility, whereas adaptive responses to vocal fundamental frequency manipulations were related to speech naturalness. Conclusions These results support that auditory-motor processes for both voice and articulatory features are intact for PwPD receiving medication. This work is also the first to suggest associations between measures of auditory-motor control and speech intelligibility and naturalness.

A neurocomputational view of the effects of Parkinson’s disease on speech production

“…Meanwhile, patients in the on-medication state may rely less on sensory mechanisms due to the positive effects of levodopa on feedforward motor control. As a result, we would expect over-exaggerated compensatory responses to reflexive pitch perturbations in the off-medication state ( Liu et al, 2012 ; Chen et al, 2013 ; Huang et al, 2016 ; Mollaei et al, 2016 , 2019 ), but not in the on-medication state ( Abur et al, 2021 ), consistent with the existing literature on auditory perturbation responses in PD.…”

“…Although impaired adaptation in response to sustained perturbations of pitch and F1 have been demonstrated in PD ( Mollaei et al, 2013 ; Abur et al, 2018 ), reflexive responses to unpredicted perturbations of pitch and loudness appear to be either normal ( Abur et al, 2021 , who tested participants on medication) or larger than normal ( Liu et al, 2012 ; Chen et al, 2013 ; Huang et al, 2016 ; 2019 ; Mollaei et al, 2016 , 2019 ; these studies tested PD participants off medication). Deep brain stimulation applied to STN has been shown to normalize the pitch shift reflex, implicating the basal ganglia in the abnormally large pitch shift reflex in PD ( Behroozmand et al, 2019 ).…”

The Effects of Electromagnetic Articulography Sensors on Speech in Individuals With and Without Dysarthria

“…Then, a perturbation is gradually introduced during a ramp-up period (e.g., shifting F1 so that /ɛ/sounds more like /i/), followed by a hold phase where the perturbation is maintained, and finally, an after-effect phase where the perturbation is removed. Although post-adaptation effects are not often the focus of these studies, they have been observed after the removal of sensorimotor perturbations for speakers with and without dysarthria secondary to PD, particularly for F1 formant perturbations (Miller et al, 2023;Purcell & Munhall, 2006;Villacorta et al, 2007;Mollaei et al, 2013;Abur et al, 2021). For instance, Abur and colleagues (2021) investigated how speakers with and without PD adapted to F1 formant shift perturbations.…”

Mechanisms of sensorimotor adaptation in a hierarchical state feedback control model of speech

“…In the context of speech production, such learning abilities have been well demonstrated by auditory-motor adaptation, in which participants modify their subsequent speech production after their auditory feedback is experimentally altered by shifting vowel formants (vocal tract resonances that distinguish vowels from one another) or vocal pitch. Speech auditory-motor adaptation remains a topic of great interest (see [1] for an extensive review on formant adaptation studies) and has been utilized to investigate speech motor control in both healthy (e.g., [2][3][4]) and clinical populations (e.g., cerebellar ataxia, [5]; Parkinson's disease, [6]; stuttering, [7]).…”