Objective: To explore temporal prediction ability as a novel pathophysiological framework in cervical dystonia.

Background: The ability to build temporal prediction (TP) is a highly flexible and adaptative system influenced by contextual factors as different predictive contexts (rhythmic or memory-based). A recent study has revealed a double dissociation in neural processes underpinning TP ability in a context-dependent manner; the basal ganglia has been involved in the formation of temporal predictions in a rhythmic context, and the cerebellum has been involved in building temporal predictions based on single-interval association (Breska 2018).

Method: Ten patients with CD (57 ± 13.4 years; 4 M) and ten healthy controls (65 ± 4.9 years; 5 M) were recruited for the study. For patients, CD severity and disability were assessed using TWSTRS and the FTM clinical rating scale for tremor to assess essential tremor. All subjects participated to the TP task. We recorded reaction times (RTs) to a target during the task in two contextual conditions of temporal anticipation: rhythmic (i.e., interstimulus intervals (ISIs) were constant) and single-interval condition (i.e., the estimation of the timing of the target was based on the prior exposure of the train of stimuli) and in a random, no temporal, condition. Two ISIs durations were explored: 600 ms (short trials) and 900 ms (long trials). We calculated for each participant an RT benefit score of the predictive condition relative to the random condition [e.g., RT(random) – RT(condition)]. We conducted a RM ANOVA on RT benefit scores with Task (2 levels: Rhythmic and Single-interval) and Duration (2 levels: Short and Long) as within factors and Group (2 levels: CD and HC) as between factors.

Results: The RM ANOVA on mean RT benefit scores revealed a significant interaction Task x Duration [p = 0.03] and a significant three-way interaction Task x Duration x Group [p = 0.045]. Post hoc analysis of the latter interaction showed that the CD group had smaller RT benefit scores for the single interval (relative to the random condition), in the long ISIs trials, compared to the HC group (p= 0.08).

Conclusion: Patients with CD exhibited a selective impairment in forming interval-based predictions. No differences were found between CD and HC groups for the rhythmic-based predictions. Such data support a cerebellar involvement in dystonia pathophysiology, as indicated in Breska (2018).

References: Breska A, Ivry RB. Double dissociation of single-interval and rhythmic temporal prediction in cerebellar degeneration and Parkinson’s disease. Proc Natl Acad Sci USA. 2018;115(48):12283–8. https://doi.org/10.1073/pnas.1810596115.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/temporal-prediction-in-cervical-dystonia/