Probing Perceptual Decision Making in Cervical Dystonia: Employment of a Novel Paradigm Integrating Behavioural and Neuronal Measures.

Cervical dystonia (CD) is a rare neurological motor disorder characterised by involuntary head and neck movements, resulting in abnormal posturing. Although CD presents clinically as a motor disorder, recent evidence suggests it is a network disorder with abnormalities in sensory and motor processing. The pathophysiology of CD remains unclear; however, it has been suggested that impairment within the superior collicular-pulvinar-amygdala network is involved. Superior Colliculus (SC) involvement may imply abnormalities in perceptual decision making (PDM). This study assessed PDM in CD and healthy controls (HC) using a novel paradigm which integrates behavioural and neuronal measures. Seven CD subjects and six HC subjects were tested. A dichromatic dynamic translational Glass pattern task was used to test PDM ability, while 24-channel EEG recordings were taken. Event related potentials were analysed, and centro-parietal positivity (CPP), a neural measure affected by PDM, was examined. Group differences were analysed using independent sample t-tests. Results revealed no statistical difference in the reaction time in the two groups, however there was a high correlation between the HC reaction time and CPP peak amplitude (R2 = 0.9876) but no correlation in the CD cohort (R2 = 0.013), suggesting the CD cohort do not generate a neural CPP response while making their decision. Furthermore, the CD group performed at a lower accuracy and slower reaction time across all coherence levels.Clinical Relevance- This work aimed to assess a potential endophenotype for CD which might lead to earlier and more accurate diagnosis and the development of novel treatment strategies. There are no previous studies relating PDM to specific neural processes in CD. This work introduces a novel paradigm which integrates behavioural and neuronal measures, allowing us to investigate the impact of CD on perceptual decision making for the first time.