Planning and executing sequential motor acts in Parkinson Disease

Many experimental evidences highlighted that Parkinson Disease (PD) patients are particularly impaired in performing a sequence of movements. In the present experiment we focused to study how PD patients plan and execute an action constituted by the sequence of reaching-grasping an object (first motor act) and placing it on a second target (second motor act). We wished to determine whether properties of the target of the second motor act influenced the kinematics of first motor act. The results showed that PD patients modified, as the controls, the initial ballistic phase of reaching according to variation of second target position (object extrinsic properties). In particular, peak accelera…