Objective: To examine temporal discrimination threshold (TDT) score across different but related forms of task-specific focal dystonia and to assess the correlation between TDT alterations and resting-state brain activity.

Background: Focal dystonia has previously been associated with prolonged TDT. However, abnormalities of temporal discrimination in musician’s dystonia are not as common as in other forms of task-specific focal dystonia. The neural alterations underlying the range of these TDT abnormalities in dystonia remain poorly understood.

Methods: Data were collected on healthy subjects (n=27), patients with musician’s dystonia (n=19) and non-musician’s dystonia (n=23). All participants completed a standard visual TDT paradigm; fifty-one participants also underwent a resting-state functional MRI scan. Between-group differences in TDT z-score were compared using non-parametric statistics (Bonferroni corrected p<0.017). Image processing followed standard protocols. Correlations between resting-state MRI and TDT z-score were examined using Spearman's rho (FWE corrected p<0.01).

Results: Differences between groups in TDT z-score were significant between healthy subjects and patients with non-musician’s dystonia (p=0.007) but not between healthy subjects and patients musician’s dystonia (p = 0.1891). Healthy subjects showed a negative correlation with TDT performance in the inferior parietal lobule (r=0.83, p<0.005). Musician's dystonia patients had negative correlations with TDT z-score in right primary motor, bilateral visual associative, right fusiform and left primary sensory cortices as well as a positive correlation in cerebellar cortex (all r<0.80), all p<0.005). Non-musician's dystonia patients showed a negative correlation only with right anterior lobe of cerebellum (r=0.54 , p<0.005). No common regions of correlations between the TDT score and resting-state brain activity were found between the groups.

Conclusions: Temporal discrimination is less affected in musician’s dystonia than non-musician’s dystonia compared to healthy subjects. Distinct neural associations may drive improved performance on TDT testing in musician’s dystonia, which suggests divergent pathophysiological mechanisms across different forms of focal task-specific dystonia.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/temporal-discrimination-threshold-is-associated-with-multiple-regions-of-resting-state-brain-activity-in-musicians-dystonia/