Recent models of the vocal sensorimotor system suggest that mechanosensory and auditory input interact to monitor voice production. Initiation of the respiratory, laryngeal, and supralaryngeal movements for voice occur prior to an audible acoustic signal. Consequently, auditory feedback alone is insufficient to guide these movements. Evidence suggests that mechanoreceptors within the laryngeal mucosa may provide perceptual and proprioceptive afference that allow interaction with auditory feedback for voice control. However, the nature of laryngeal mechanosensory monitoring and its interaction with auditory feedback are poorly understood. The distinct voice disorders commonly observed in Adductor Spasmodic Dysphonia (ADSD) and Parkinson's Disease (PD) may each be uniquely associated with abnormal mechanosensory and auditory monitoring of voice production. This view is reinforced by current approaches to voice therapy that emphasize the importance of sensory monitoring and by recent evidence of sensory responses to botulinum toxin. However, the distinct sensory mechanisms associated with each of these voice disorders and how these mechanisms may respond to intervention remain largely unexplored. We will combine mechanosensory and auditory techniques developed in our laboratories to directly assess the mechanosensory and auditory mechanisms of the vocal sensorimotor system and the interaction between these sensory modalities in healthy participants and clinical participants with ADSD and PD. We have two specific aims: (1) To determine if mechanosensory monitoring is modulated during voice production and how it interacts with auditory feedback - to expand our understanding of the vocal sensorimotor system; (2) To define the association between voice-related sensory monitoring with voice severity and voice improvement in ADSD and PD. Based on our preliminary data, we hypothesize that mechanosensory monitoring is modulated during healthy voice production and interacts with auditory feedback to maintain voice in the presence of laryngeal sensory input. Based on our preliminary clinical data, we hypothesize that abnormal sensory monitoring is uniquely associated with voice disturbances in ADSD and PD and that each will improve with intervention. We have developed a sensorimotor assessment battery to define the sensory pathophysiology of ADSD and of PD. Our assessments will be immediately applied in the clinical setting to gauge severity and treatment response. Therefore, the scientific impact and clinical translation of this programmatic research is immediate. Our collaborative team is in a unique position to integrate mechanosensory and auditory assessment techniques. Our approach will substantially expand basic knowledge about the vocal sensorimotor system and will offer powerful insights into the distinct sensory mechanisms of ADSD and of PD. Therefore, our studies will have a high overall impact, setting the stage for future hypothesis-driven studies of the associated neural pathways and innovative sensory-based medical and behavioral approaches to voice care.
Recent scientific models of healthy voice control suggest that sensory information from the larynx and from hearing are important to guide voice-related movements. However, it is unknown how abnormal sensory mechanisms may be associated with voice disorders or how these mechanisms may improve with treatment. We will use assessment techniques developed in our laboratories to directly test sensory mechanisms of voice control in healthy participants and in clinical participants with voice disorders associated with Adductor Spasmodic Dysphonia and Parkinson's Disease. Our ability to directly assess sensory mechanisms associated with these voice disorders and our ability to gauge improvement in these mechanisms is highly significant. This work will offer powerful insights that may directly impact strategic approaches to voice treatment.
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