Dysarthria in people with Parkinson's disease (PD) has been widely studied. However, a limited number of studies have investigated lingual function during speech production in this population. This study aimed to investigate lingual kinematics during speech production using electromagnetic articulography (AG-200 EMA). The PD group consisted of eight dysarthric speakers with PD and was matched with a group of eight controls. The tongue tip and tongue back movements of all participants during sentence production were recorded by EMA. Results showed that, perceptually, the participants with PD were mildly dysarthric. Kinematic results documented comparable (for alveolar sentence production) and increased (for velar sentence production) range of lingual movement in the PD group when compared to the control group. Lingual movement velocity, acceleration, and deceleration were also increased in the PD group, predominantly for the release phase of consonant production during sentence utterances. The PD group had longer duration in the production of alveolar consonant and comparable duration in the production of velar consonant. The results of the present study suggest the presence of impaired lingual control in individuals with PD. Increased range of articulatory movement, primarily in the release phase of consonant production, may account for articulatory imprecision in this population.

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Articulatory dysfunction is recognised as a major contributor to the speech disturbances seen in Parkinson's disease (PD). The present study aimed to compare lingual kinematics during consonant production within a sentence in eight dysarthric (DPD) and seven nondysarthric (NDPD) speakers with PD with those of eleven nonneurologically impaired normal participants. The tongue tip and tongue back movements of the participants during sentence production were recorded using electromagnetic articulography (EMA). Results showed that both the DPD and NDPD had deviant articulatory movement during consonant production that resulted in longer duration of consonant production. When compared with the NDPD group, the DPD group primarily exhibited increased range of lingual movement and compatible duration of production with an accompanying increase in maximum velocity, maximum acceleration, and maximum deceleration. These findings are contrary to proposed theories that suggest articulatory imprecision in dysarthric speakers with PD is the outcome of reduced range of articulatory movement.

The findings revealed that a single session of anodal tDCS over the Broca's area did not significantly improve speech production during tongue twister production.