Behavioral effects arising from the neural substrates for atypical planning and execution of word production in stuttering

This article reports on an fMRI study that examined the neural bases of atypical planning and execution processes involved in stuttering (Lu et al., 2010). In the study, twelve stuttering speakers and 12 controls named pictures which required single-syllable, multi-syllable, or repeated-syllable word responses, in the scanner. The factors associated with planning and execution were: (1) number of syllable-sized motor programs; and (2) syllable size and onset complexity. Structural equation modeling revealed two parallel neural circuits (the basal ganglia–inferior frontal gyrus, premotor area circuit and the cerebellum–premotor area circuit). These were involved in atypical planning and execution processes in stuttering, respectively. The interface between planning and execution in stuttering involved the angular gyrus. This article discusses the relevance of these findings to behavioral theories that also propose separate planning and execution mechanisms behind stuttering.