Cervical dystonia (CD), a hyperkinetic motor neurological disorder, is the most common phenotype of Adult Onset Idiopathic Focal Dystonia, resulting in involuntary movements and postures where pathophysiology remains elusive. Diagnosis of the disorder relies on clinical judgement due to the heterogeneous nature making it difficult to research and track. The Superior colliculus (SC) is a conserved midbrain structure that receives topographically organised information and is involved in many afferent and efferent pathways related to orientation, avoidance, defensive and approach behaviour, and head and neck movements following gaze shifts through saccades. Aberrant midbrain networks and their connectivity has been increasingly recognised, accounting for the ‘pre-motor’ and ‘non-motor’ syndrome of CD. Altered GABAergic physiology is thought to be the primary pathomechanism resulting in disinhibition and over-activation of SC with impaired sensorimotor and emotional stimuli processing with poor target selection and spatial attention. The reduced regulation of the ‘ON-pause-OFF’ pattern is also thought to be affected in CD.
Perceptual decision-making, an example of embodied cognition, is thought to be impaired in CD due to disordered SC processing. Although there is literature discussing SC in CD pathophysiology and perceptual decision-making, limited publications describe the interaction between these two areas. From the available literature, it can be hypothesised that an impairment in attentional processes involving visual attention, saliency and saccades, reaction time, perceptual confidence and use of priors is likely involved.
This project will investigate perceptual decision-making using an adapted orientation discrimination task in Cervical Dystonia patients, their unaffected first-degree relatives and healthy controls. EEG recordings will be made to provide an objective neural signature of perceptual decision-making.
This project will be in conjunction with the Department of Neurology at St. Vincent’s University Hospital. Research Ethics Approval is under review to test perceptual decision-making in a cohort of people with focal dystonia and healthy controls.