Distribution of Tourette's verbal tics produced during active speech

Abstract

Tourette syndrome causes individuals to produce unwanted movements and vocalizations called tics. Verbal tics are those tics that closely mimic words/phrases—their execution requires the same set of articulators needed to produce speech. Tics respond to a preceding urge to tic and are akin to other urge-based actions like cough. Urges to tic can arise at any time but speech and tics must be deployed sequentially as they cannot be produced simultaneously. How are conflicts between the speech and tic motor systems resolved? This study tests the prediction that tics interfere with production of words and intonational phrases less frequently than expected by chance. As predicted, pilot data from one subject showed that the expected probability of words and tics co-occurring were these events independent was significantly higher than the observed likelihood of tics interrupting words. Correspondingly, the likelihood of intonational phrase-final boundaries co-occurring with tics if these events were independent was significantly lower than the observed probability of tics given intonational phrase-final boundaries. Data from multiple people with Tourette’s will be presented. Results suggest that utterances are “protected” from tic interruptions, providing evidence that the tic and speech motor systems are linked in production. [Work supported by NIH and NSF.]