Jenn Segawa & Frank Guenther

Speech Laboratory, Department of Speech, Language and Hearing Sciences, Boston University 

Although much is known about the neural mechanisms of learning motor sequences for non-speech tasks, surprisingly little is known about the neural bases of speech sequence learning despite its importance in the development and maintenance of efficient articulatory movements. To identify the brain network that supports this skill, we combined behavioral measures of learning with fMRI and DTI scans of English speakers learning to produce novel syllables that are phonologically illegal in English but legal in another natural language. Our fMRI results show that although the speech sequencing network overlaps substantially with brain areas known to be involved in other primate motor sequencing tasks, it also involves speech-specific areas of the left prefrontal cortex and posterior superior temporal cortex. In addition, we found that learning ability correlated with BOLD signal decreases in the frontal operculum-anterior insula and with white matter integrity under the posterior superior temporal gyrus. These findings suggest that speech motor sequence learning relies not only on brain areas involved in general motor sequencing learning but also those associated with auditory feedback learning. Moreover, an individual’s learning success may be modulated by the structural connectivity integrity underlying these motor and sensory brain regions.