Supplementary Material for: Functional Correlates of Increasing Gestural Articulatory Fluency Using a Miniature Second-Language Approach

Objectives: Gesture-based second languages have become an important tool in the rehabilitation of language-impaired subpopulations. Acquiring the ability to use manual gestures as a means to construct meaningful utterances places unique demands on the brain. This study identified changes in the blood oxygen level-dependent (BOLD) signal associated with the development of gestural fluency using a miniature second-language-based approach. Participants and Methods: Twelve healthy right-handed adults (19-31 years) were trained to produce sequences of meaningful gestures over a period of 2 weeks. Functional magnetic resonance imaging was used to identify brain regions involved in actual and imagined production of meaningful sentences both before (nonfluent production) and after (fluent production) practice. Results: Brain areas showing learning-dependent increases in activity associated with the development of fluency included sites associated with language articulation, while learning-related decreases in the BOLD signal were observed in cortical networks associated with motor imagery, and native language processing. Conclusion: These findings provide novel insights regarding the neural basis of fluency that could inform the design of interventions for treating speech disorders characterized by the loss of fluency.