title: Lack of non-voluntary stepping responses in Parkinson's disease.
abstract: The majority of research and therapeutic actions in Parkinson's disease (PD) focus on the encephalic areas, however, the potential involvement of the spinal cord in its genesis has received little attention. Here we examined spinal locomotor circuitry activation in patients with PD using various types of central and peripheral tonic stimulation and compared results to those of age-matched controls. Subjects lay on their sides with both legs suspended, allowing low-friction horizontal rotation of the limb joints. Air-stepping can be used as a unique and important model for investigating human rhythmogenesis since its manifestation is largely facilitated by the absence of external resistance. In contrast to the frequent occurrence of non-voluntary stepping responses in healthy subjects, both peripheral (muscle vibration) and central (Jendrassik maneuver, mental task, Kohnstamm phenomenon) tonic influences had little if any effect on rhythmic leg responses in PD. On the other hand, a remarkable feature of voluntary air-stepping movements in patients was a significantly higher frequency of leg oscillations than in age-matched controls. A lack of non-voluntary stepping responses was also observed after dopaminergic treatment despite the presence of prominent shortening reactions (SRs) to passive movements. We argue that the state and the rhythmogenesis capacity of the spinal circuitry are impaired in patients with PD. In particular, the results suggest impaired central pattern generator (CPG) access by sensory and central activations.
authors: Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia.
authors: V A
authors: VA
authors: Selionov
authors: I A
authors: IA
authors: Solopova
authors: D S
authors: DS
authors: Zhvansky
authors: A V
authors: AV
authors: Karabanov
authors: L A
authors: LA
authors: Chernikova
authors: V S
authors: VS
authors: Gurfinkel
authors: Y P
authors: YP
authors: Ivanenko
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D000843:Ankle Joint / Q000503:physiopathology; D000978:Antiparkinson Agents / Q000627:therapeutic use; D001696:Biomechanical Phenomena; D003627:Data Interpretation, Statistical; D004576:Electromyography; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006621:Hip Joint / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008124:Locomotion / Q000502:physiology; D008297:Male; D008606:Mental Processes / Q000502:physiology; D008875:Middle Aged; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology; D009460:Neurologic Examination; D010300:Parkinson Disease / Q000503:physiopathology*; D019415:Torque; D014732:Vibration; D016138:Walking / Q000502:physiology
chemical_list: D000978:Antiparkinson Agents