| Normal speech production is relegated to near automaticity and is dependent upon a highly coordinated coupling of motor output with sensory input from auditory and somatosensory (i.e., sensory inputs from skin, mucosa, muscle and joint receptors) systems. Models of sensorimotor dysfunction, such as Parkinson's disease (PD), demonstrate evidence of substantially impoverished sensorimotor integration and degradation of motor control. Few studies have examined the relations between changes in sensorimotor integration and speech motor control in diseases such as PD. Previous psychophysical studies and clinical reports described decreased somatosensory detection and decreased somatosensory awareness of vocal tract deficits in individuals with PD. However, no studies have examined the relation between laryngeal mechanosensory detection and degradation in laryngeal motor control in PD. Therefore, the purpose of this study was to use laryngeal mechanosensory detection thresholds and aerodynamic measures of laryngeal engagement to examine the potential relation between deficits in laryngeal somatosensory detection and control of speech-related laryngeal movements in a group of participants with PD and a group of normal controls.; Data from this study yielded four primary findings. (1) Individuals with PD exhibited aberrant timing of vocal fold medialization compared with normal controls. (2) Individuals with PD exhibited higher laryngeal mechanosensory detection thresholds than normal controls. (3) Individuals with PD exhibited a larger magnitude of asymmetry in laryngeal mechanosensory detection thresholds than normal controls. (4) Laryngeal mechanosensory detection thresholds were significantly correlated with aberrant timing of vocal fold medialization, aberrant scaling of lung volume utilized for speech, severity of voice, and severity of PD. |
