PhD ceremony Ms. A. van der Hoorn: Hemisphere-specific support of visuomotor control in Parkinson's Disease

PhD ceremony: Ms. A. van der Hoorn

Dissertation: Hemisphere-specific support of visuomotor control in Parkinson's Disease

Promotor(s): prof. K.L. Leenders, prof. B.M. de Jong

Faculty: Medical Sciences

Parkinson’s disease is a common neurological movement disorder due to a dopamine deficit within the brain. Symptoms are most pronounced on one side of the body. It is currently unknown why this asymmetry occurs. In this thesis, we demonstrated that the hemisphere dominant for handedness is more vulnerable for developing Parkinson’s disease. Showing this relation provides clues to further elaborate this characteristic asymmetry in Parkinson’s disease.

Furthermore, we investigated freezing of gait in Parkinson patients. During freezing, it feels like the feet are glued to the ground. It was previously suggested that freezing might be related to right hemisphere dysfunction. We thus expected that freezing would be more prevalent in patients with mainly right hemisphere involvement, with symptoms most pronounced on the left body side. We were unable to show this in our retrospective database study. However, a prospective study by others did. We further studied the mechanism behind freezing of gait with manipulation in a visual motion pattern (optic flow). Mimicking approaching a narrow passage, which may provoke freezing of gait, requires to switch from external support of movement to internal generation of movements. We showed that this shift is disturbed in Parkinson patients by demonstrating deterioration of gait during treadmill gait as well as disturbed brain activations during functional MRI scans.