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

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.