Body posture and motor imagery in Parkinson's Disease

Parkinson's Disease is characterized by motor impairments such as tremor,
bradykinesia and hypokinesia. Traditionally, it is thought that there is a
direct relationship between impaired basal ganglia function and these motor
impairments. However, since 20 years there is an increasing amount of evidence
that motor impairments might also be caused trough an indirect causal
relationship.

Namely, it has been found that PD patients exhibit, besides motor impairements,
disturbances in proprioception. Proprioception is a sense that allows humans to
notice the position of their own body in space. Little organs in muscles,
tendons and joints sense the muscle tension and angle of the joints and convey
that information to the brain. Reserach has demonstrated that the impairements
in proprioception in PD patients is caused by disturbed central processing of
these proprioceptive signals. Normal prioprioception is essential for normal
movements. This research has lead to the belief, that in PD disturbed
proprioception may contribute to the motor disturbances.

However, until present it is unclear whether disturbed proprioception leads to
disturbances on the level of motor planning. That means, that because of
distubed proprioception the position of body parts is inadequately registered
by the brain, which could lead to a distubed motor plan. Furthermore, it is
unclear which brain structures are involved in these disturbances. Previous
research by our group in healthy volunteers has shown that this coupling
between position of the body part and the motor plan is made in the posterior
parietal cortex. We want to investigate whether this brain region functions
adequately in PD patients. This would provide important insights in the
pathophysiological mechanism in PD, and it may also provide us with
opportunities to develop therapeutical strategies aimed at restoring normal
activity in this brain region.

Investigate whether in Parkinson's Disease a disturbed body schema (awareness
of one' own body posture) leads to disturbed motor planning, and whether brain
regions involved in this process show an impaired activity.

observational

This research holds no risks at all for the patients involved. The burden
consists of taking part in this research for three hours. During these three
hours, the patient lies in an MRI scanner for about one hour, of which he/she
has to concentrate on an experimental task for 40 minutes.