Saccades changes in patients with Parkinson’s disease
The goal of our study was to figure out the dynamic of neurodegeneration in healthy subjects, patients with Parkinson’s disease (PD) and progressive supranuclear palsy (PSP) and to compare processes of pathological neurodegeneration and normal aging. For these purposes we registered saccadic eye movements using electrooculography. 27 patients with PD, 5 patients with PSP and 52 healthy volunteers took part in the study. To analyze aging dynamic all participants were divided into matching age groups.
In healthy volunteers the mean saccade latency and the percentage of multistep saccades increase significantly after the age of 60. Values of these characteristics in patients with PD significantly exceed the values in the corresponding age groups of healthy subjects. The duration of single saccades depends on age to a smaller extent and does not change in patients with PD. In patients with PSP eye movement abnormalities are more salient than in patients with PD. Restriction of vertical gaze in PSP appears even on early stages of disease. As the disease progresses oculomotor abnormalities became more pronounced: decreasing of saccades amount, limitation of vertical and horizontal gaze and eye movements mismatch were revealed.
Thereby the saccades characteristics analysis allows us to reveal the rate of neurodegeneration that may be useful for early diagnostics and treatment control.
The human motor cortex is involved in the planning and execution of movements as well as in the processing of action language, and it is impaired in Parkinson's disease (PD) as a consequence of dopamine degeneration. The aim of this study is to understand the role of dopamine in the processing of action words by looking at PD patients with and without medication. A group of 23 healthy controls and 34 non-demented PD patients participated in an action verbal fluency task on and off dopamine medication. A repeated measures 2 × 2 ANOVA was conducted with dopamine (on/off) and type of verb (high and low specificity motor verbs) as independent variables and the number of words generated as a dependent variable. Our results showed that patients on dopamine medication produced a significantly greater number of high specificity motor verbs than low ones. In contrast, patients off dopamine medication generated a similar number of verbs with high and low motor specificity. MANOVA analyses showed a significantly lower production of verbs with high motor specificity on PD patients off medication compared to healthy controls. However, performance of PD patients in the on condition was similar to that found in healthy controls. In conclusion, the dopamine network from basal ganglia to brain motor areas might play a role in retrieving action verbs with specific semantic representations.