Stuttering and natural speech processing of semantic and syntactic constraints on verbs.

PURPOSE Previous findings from event-related brain potentials (ERPs) indicate that adults who stutter (AWS) exhibit processing differences for visually presented linguistic information. This study explores how neural activations for AWS may differ for a linguistic task that does not require preparation for overt articulation or engage the articulatory loop for silent speech. METHOD Syntactic and semantic processing constraints were examined in AWS and adults who are normally fluent (AWNF) by assessment of their behavioral performance and ERPs in a natural speech listening task. RESULTS AWS performed similarly to AWNF in identifying verb-agreement violations and semantic anomalies, but ERPs elicited by syntactic and semantic constraints indicated atypical neural functions for AWS. ERPs of the AWNF displayed an expected N400 for reduced semantic expectations and a typical P600 for verb-agreement violations. In contrast, both N400s and P600s for the semantic and verb-agreement conditions were observed in the ERPs of the AWS. CONCLUSIONS The findings suggest that AWS may engage semantic-syntactic mechanisms more generally for semantic and syntactic processing. These findings converge with earlier studies using visual stimuli to indicate that whereas linguistic abilities are normal in AWS, underlying brain activity mediating some aspects of language processing may function differently.