Postural deficits in Parkinson's disease are caused by insufficient feedback motor error correction and by deficits in sensory reweighting

The presence of postural instability separates mild Parkinson's disease (PD) (Hoehn and Yahr stages 1 and 2) from moderate and severe PD (Hoehn and Yahr stages 3–5); quality of life inexorably deteriorates for patients with moderate or severe PD. Despite the severe consequences associated with falling and instability, the origin of these disturbances with relation to the motor control process is not understood. Methods: Here we studied motor control of posture in a total of 16 PD patients under chronic subthalamic nucleus (STN) stimulation and 15 age-matched healthy control subjects using a model based approach.…