Mirror neurons as a model for the science and treatment of stuttering.

Persistent developmental stuttering is generally considered a speech disorder and affects ∼1% of the global population. While mainstream treatments continue to rely on unreliable behavioral speech motor targets, an emerging research perspective utilizes the mirror neuron system hypothesis as a neural substrate in the science and treatment of stuttering. The purpose of this exploratory study is to test the viability of the mirror neuron system hypothesis in the fluency enhancement of those who stutter. Participants were asked to speak while they were producing self-generated manual gestures, producing and visually perceiving self-generated manual gestures, and visually perceiving manual gestures, relative to a nonmanual gesture control speaking condition. Data reveal that all experimental speaking conditions enhanced fluent speech in all research participants, and the simultaneous perception and production of manual gesturing trended toward greater efficacious fluency enhancement. Coupled with existing research, we interpret these data as suggestive of fluency enhancement through subcortical involvement within multiple levels of an action understanding mirror neuron network. In addition, incidental findings report that stuttering moments were observed to simultaneously occur both orally and manually. Consequently, these data suggest that stuttering behaviors are compensatory, distal manifestations over multiple expressive modalities to an underlying centralized genetic neural substrate of the disorder.