PhD defense Lauriane Veron-Delor

Because of its high level of automaticity, handwriting appears particularly vulnerable to Parkinson’s disease (PD). Dysgraphia in PD manifests as a significant decrease in size, velocity and fluency of movement. Designed around four studies, this thesis aimed to characterise dysgraphia in PD at behavioural and cerebral levels, and to evaluate the effect of background music and musical sonification in the rehabilitation of writing disorders. We showed that movement fluency of spatially constrained spiral production was a relevant variable to evaluate the changes induced by PD and the effects drug treatment. Also, movement velocity in signature was an interesting parameter allowing to discriminate healthy participants from patients with treatment. The use of background music showed significant effects on handwriting disorders in a young patient, whereas its potential seemed less relevant compared to that of musical sonification for dysgraphia in PD. To better understand the effect of a basal ganglia PD dysfunction on handwriting, we manipulated its sequential (succession of strokes to form letters) and spatial adaptation components (pen movement under spatial constraints) in an fMRI study. Initially performed in young participants, this study clarified the functional role of three key regions of the writing brain network: the left dorsal premotor cortex, the left superior parietal lobule and the right cerebellum.