Poster D12, Wednesday, August 21, 2019, 5:15 – 7:00 pm, Restaurant Hall
Stuttering and the Social Brain
Eric S. Jackson1, Swethasri Dravida2, Vincent Gracco3, Xian Zhang1, Adam Noah1, Joy Hirsch1;1New York University, 2Yale School of Medicine, 3Haskins Laboratories
Functional neuroimaging studies of individuals who stutter have revealed a number of brain-based differences such as reduced activation in left hemisphere and elevated activation in right hemisphere sensorimotor networks. However, a significant area that has seen less focus is the contribution from social-cognitive networks. This limitation is problematic and theoretically and clinically relevant because stuttering occurs primarily during social interaction, presumably engaging social-cognitive processes. The current work extends the study of stuttering from sensorimotor control into the social-cognitive domain. We test the general hypothesis that social-cognitive processing de-stabilizes the speech motor systems of adults who stutter (AWS), which is reflected by atypical neural activation in social-cognitive regions (e.g., temporoparietal junction [TPJ], dorsomedial prefrontal cortex [DMPFC]) in addition to commonly reported findings of reduced activation in left hemisphere speech-language regions (i.e., inferior frontal and superior temporal gyrus [IFG/STG]). To do this, we examine the neural impact of social interaction (i.e., the presence of a communicative partner) on 22 AWS and 22 age-matched controls (CON) using functional near-infrared spectroscopy (fNIRS) to detect changes in blood flow concentrations during relatively natural conditions (e.g., face-to-face speech interaction while participants sit upright). As a result, we evaluate neural activation in the context in which stuttering primarily occurs: social and communicative speech. In this study, there were two conditions during which participants responded to questions asked by the examiner, who was in the testing room (social), and the same questions presented via audio recordings of the examiner while the participant was alone in the testing room (alone). The questions were followed by a five-second preparatory period after which participants verbally responded while looking at the examiner. Neural signals associated with the preparation period (prior to the onset of speech) were analyzed using the general linear model. Results indicate that compared to the CON, the AWS exhibited lesser activation in left IFG and left STG in the social > alone contrast. Posthoc testing revealed that both groups exhibited an increase in activation during the social condition, but the increase was significantly greater in the CON indicating that the commonly reported findings of reduced activation in left IFG/STG may be more related to social-cognitive than sensorimotor demands. In addition, the AWS exhibited greater activation in right TPJ and lesser activation in right DMPFC in the social > alone contrast. It appears that the AWS were less able to inhibit activity in right TPJ under increased social demands, as well as less able to recruit necessary resources for speech interaction (e.g., attention, inhibition) in frontal regions (right DMPFC). Overall, our results suggest that AWS exhibit atypical neural function in both speech-language and social networks during social and communicative speech. These findings highlight the importance of focusing on social-cognitive in addition to speech-language networks, as well as the benefits of using approaches (fNIRS) that facilitate increased ecological validity during neural data collection in stuttering research.
Themes: Disorders: Developmental, Speech Motor Control
Method: Functional Imaging