Classification of Types of Stuttering Symptoms Based on Brain Activity

Among the non-fluencies seen in speech, some are more typical (MT) of stuttering speakers, whereas others are less typical (LT) and are common to both stuttering and fluent speakers. No neuroimaging work has evaluated the neural basis for grouping these symptom types. Another long-debated issue is which type (LT, MT) whole-word repetitions (WWR) should be placed in. In this study, a sentence completion task was performed by twenty stuttering patients who were scanned using an event-related design. This task elicited stuttering in these patients. Each stuttered trial from each patient was sorted into the MT or LT types with WWR put aside. Pattern classification was employed to train a patient-specific single trial model to automatically classify each trial as MT or LT using the corresponding fMRI data. This model was then validated by using test data that were independent of the training data. In a subsequent analysis, the classification model, just established, was used to determine which type the WWR should be placed in. The results showed that the LT and the MT could be separated with high accuracy based on their brain activity. The brain regions that made most contribution to the separation of the types were: the left inferior frontal cortex and bilateral precuneus, both of which showed higher activity in the MT than in the LT; and the left putamen and right cerebellum which showed the opposite activity pattern. The results also showed that the brain activity for WWR was more similar to that of the LT and fluent speech than to that of the MT. These findings provide a neurological basis for separating the MT and the LT types, and support the widely-used MT/LT symptom grouping scheme. In addition, WWR play a similar role as the LT, and thus should be placed in the LT type

An anterior-posterior gradient of cognitive control within the dorsomedial striatum

Lateral prefrontal cortex and basal ganglia work together to mediate working memory and top-down regulation of cognition. This circuit regulates the balance and interactions between automatic and high-order control responses. Using ultra-high-field high-resolution functional magnetic resonance imaging (7 T-fMRI), the present study examined the role of subcortical structures in cognitive control during language processing. Participants were asked to judge the grammaticality of unambiguous, ungrammatical and ambiguous sentences. Grammatical unambiguous sentences should elicit an automatic response, while ambiguous and ungrammatical sentences should conflict with the automatic response and, hence, require a high-order control response. Within the control response domain, ambiguity and ungrammaticality represent two different dimensions of conflict resolution, while for a temporarily ambiguous sentence a correct interpretation is available, that is not the case for ungrammatical sentences. Our results reveal an anterior–posterior axis in the dorsomedial striatum with more rostral regions supporting higher levels of cognitive processing. This functional architecture mirrors the rostrocaudal hierarchical organization evidenced within the lateral prefrontal cortex