Project Summary: When planning a movement towards a visual target, the sensorimotor nervous system is engaged to estimate the spatial location of the target and correspondingly perform the motor output to reach it. Movements can be planned in two major coordinate frames: the intrinsic, body-centered frame and the extrinsic, world-centered frame. Until now, it has been supposed that only one of these frames were engaged defined by two different starting arm configurations (that means body positioning) while they perform the same experiment. during motor control. The purpose of this study is to show that the intrinsic- and the extrinsic frames can coexist and both contribute to the motor adaptation during a visuomotor rotation movement task. Several neural substrates are supposed to be engaged in the motor learning such as the primary cortex (M1), the Supplementary Motor Area (SMA), the cerebellum and possibly the parietal cortex. In Parkinson’s disease, these motor regions are strongly affected. It is in our interest to study the internal representation of visuomotor rotation learning in PD patients compared to healthy patients. This knowledge could lead to the design of procedures for motor training and rehabilitation in a near future.