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Poster C24, Thursday, November 9, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Speeded grammatical processing in Tourette syndrome

Cristina Dye1, Matthew Walenski2, Adam Takacs3, Karolina Janacsek4, Andrea Kobor4, Dezso Nemeth4, Stewart H. Mostofsky5, Michael T. Ullman6;1Newcastle University, United Kingdom, 2Northwestern University, United States, 3University of Glasgow, United Kingdom, 4Eötvös Loránd University, Hungary, 5Johns Hopkins University, United States, 6Georgetown University, United States

Introduction. Tourette syndrome (TS) is a neurodevelopmental disorder characterized by motor and vocal tics, and is associated with frontal/basal ganglia abnormalities. Whereas previous research has revealed various cognitive strengths in other neurodevelopmental disorders, less attention has been paid to potential strengths in TS. Additionally, there is very little evidence of strengths in the domain of language in any neurodevelopmental disorder. Here we examine the hypothesis that grammatical processing might be speeded in TS, and that this may be related to enhanced procedural memory, which underlies grammar. Methods. In a series of experiments, we tested grammatical processing and procedural memory in children with TS and matched typically developing (TD) children (Walenski et al., 2007; Dye et al., 2016; Takacs et al., under review). In Experiment 1, we tested TS and TD performance at morphology, specifically in the production of regular past-tense forms, which are posited to be combined with the grammatical/procedural system (e.g., walk + -ed), and matched irregular forms, which are posited to depend on memorized representations (e.g., dug). In Experiment 2, we tested phonology, specifically in a non-word repetition task (repetition of complex phonological sequences; e.g., /naıtʃoʊveıb/), which is thought to depend on the grammatical (de)composition of phonological segments. In Experiment 3, we comprehensively examined procedural learning, from memory formation to retention, in an implicit sequence learning task (Alternating Serial Reaction Time Task) performed over two days. Results. In Experiment 1, the TS children were significantly faster than TD children at producing rule-governed past-tenses (slip–slipped, plim–plimmed, bring–bringed) but not irregular (ized) past-tenses (bring–brought, splim–splam). In Experiment 2, the TS children showed speeded repetition of non-words, especially for longer forms, which require more (de)composition. There were no TS/TD accuracy differences at either the morphology or phonology tasks. In Experiment 3, the children with TS showed sequence knowledge advantages as compared to the TD children on both days, suggesting enhanced procedural learning and retention. Moreover, in Experiment 1, children with TS also showed speeded naming of manipulated (hammer) but not non-manipulated (elephant) items, suggesting that the processing of (procedural) motor skill knowledge may also be speeded in TS. Summary and conclusion. In sum, children with TS showed evidence for speeded grammatical composition in both morphology and phonology, suggesting the possibility that grammatical composition is speeded more generally in the disorder. Given independent evidence tying grammar to procedural memory (e.g., Ullman, 2004, 2016), and the evidence presented here that the learning, retention, and processing of (non-linguistic) procedural memory is enhanced in TS, the grammatical enhancements in TS may be related to underlying enhancements of procedural memory. In turn, we suggest that this pattern may be best explained by the same frontal/basal ganglia abnormalities that lead to tics, which are also characterized by their rapidity. Thus, it may be that pathological abnormalities leading to dysfunction may also lead to at least certain advantages.

Topic Area: Language Development

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