Locomotor issues in parkinsonian's mesencephalic locomotor region and subthalamic nucleus
Parkinson disease (PD) is the most common movement disorder. Dysfunction of basal ganglia circuits in PD leads to characteristic motor deficits including bradykinesia, with hypometria and reduced EMG activity, tremor, and frequently gait disorders with start hesitation or freezing of gait (FOG) associated with increased falling. On the one hand, there is a large literature on the postural adjustments during gait initiation and the biomechanics of ongoing gait in healthy and patient populations. On the other hand, neuronal recording in the pallidum, subthalamic nucleus (STN), substantia nigra pars reticulata (SNpr) and mesencephalic locomotor region (MLR) demonstrate activity related to movement and locomotion in rats, cats, primates and humans. DBS, particularly STN- and MLR-DBS, can effectively alleviate postural and locomotor deficits in PD, although the neural mechanisms and the precise role of each structure in locomotion is still matter of debate. The aim of this study is to characterize the association between STN and MLR neuronal activity and the biomechanical parameters of locomotion and gait initiation. I will characterize these associations in PD patients using neuro-muscular, neuro-kinematic and neuro-neuronal (STN-STN, MLR-MLR) coherence in different locomotor paradigms under different treatment conditions. This study will make an important contribution to a poorly studied but important aspect of motor control in PD. From a knowledge transfer point of view, it will provide important information to clinicians and researchers using DBS to ameliorate postural difficulties and FOG. From an interdisciplinary point of view, it will help neurologists to refine diagnosis as well as foster the core of knowledge and help targeting new avenues of treatment to rehabilitation professionals involved in the non-invasive treatments of PD.