Optimizing the Social Engagement System in Prader-Willi Syndrome: Insights From the Polyvagal Theory

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The Polyvagal Theory focuses on how function and structure changed in the vertebrate autonomic nervous system during evolution. The theory is named for the vagus, a major cranial nerve that regulates bodily state. As a function of evolution, humans and other mammals have a "new" vagal pathway that links the regulation of bodily state to the control of the muscles of the face and head including the middle ear muscles. These pathways regulating body state, facial gesture, listening (i.e., middle ear muscles), and vocal communication collectively function as a Social Engagement System (SES). Because the Social Engagement System is an integrated system, interventions influencing one component of this system (e.g., middle ear muscles) may impact on the other components. Individuals with Prader-Willi Syndrome (PWS) exhibit many behaviors that are consistent with a compromised Social Engagement System. Atypical function of the Social Engagement System results in problems associated with state regulation (e.g., impulsivity, tantrums, and difficulty with change in routine), ingestion (e.g., difficulties in sucking at birth, hyperphagia), coordination of suck/swallow/breathe, intonation of vocalizations, auditory processing and hypersensitivity, and socialization. We propose to confirm that several features of the behavioral phenotype of PWS may be explained within the context of a dysfunctional SES (Specific Aim I), which may be partially rehabilitated via an intervention designed as a 'neural exercise' of the SES (Specific Aim II). Specific Aims: Aim I: To demonstrate that children with PWS have atypical regulation of the SES. We hypothesize these effects will be manifested by dampened vagal regulation of the heart (low parasympathetic tone); poor middle ear muscle regulation resulting in auditory hypersensitivities and poor auditory processing; lack of voice intonation (prosody), and difficulties in accurately detecting the emotions of others. Aim II: To demonstrate the effectiveness of the Listening Project Protocol (LPP) in decreasing the atypical features of the SES in adolescents with PWS. We hypothesize that individuals who complete the LPP will have improved vagal regulation of the heart, improved middle ear muscle regulation, increased voice intonation and improved ability to accurately detect the emotions of others.

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